DNA Case Study: Hayden Family

So far, my typical DNA connections consist of picking a DNA match and trying to piece together a family tree that connects to my own. This is sometimes successful. Sometimes I ask for help from the DNA match, who sometimes replies. It usually involves lots of work. And as I continue down my list of DNA matches, toward more distant relations, it gets harder and harder.

My Hayden family connection was different. While exploring match profiles on 23andMe, I noticed several that seemed grouped together, frequently showing up as common matches. Almost all replied to my messages. Almost all had researched their genealogies extensively. I fairly quickly established that the common family was the Haydens. Some put me in contact with other Hayden family genealogists. One had attached resources to a Hayden tree on FamilySearch, and also replied to my message. After gathering their information and researching the gaps, I was able to assemble a skeletal family tree, just connecting the DNA matches, not including their families and ancestors families that I have typically included in my tree. I then tried to connect my own Hayden ancestor to their tree. No census records together, no Irish baptismal record, no FamilySearch, Rootsweb, message board, FindAGrave, Google, or other public data information. None of the matches had among their records any mention of my ancestor.

Anne Hayden Campbell

One of my matches referred me to an article they had written many years ago in which I recognized a photograph that had been hanging on my parents' wall for decades, in what they called the "Rogues Gallery", their photos of their ancestors. While my match had guessed at the the identity of the person, ours was labeled Anne Hayden Campbell by one of Anne's grandchildren. So although I was not finding the family connection, this photograph implied that there was a connection and that most likely their Hayden family was my own.

Now I wondered, if my Anne was part of this Hayden family, where would she fit in? All of the others traced back to Martin and Katherine Headen, born in 1796 and ca. 1790, respectively, in Ireland. The baptisms of many of their children took place in the Catholic parish of Myshall in County Carlow, where records state the family lived in the town of Shangarry. The known birth dates were in 1817, 1822, 1825, and 1832. Anne was born between about 1823 and 1826, so would fit nicely into an unusual gap in children. Baptismal records in those early years were infrequent, so she could simply have been missed. But Anne could also have been Martin's niece, in a different branch of the family.

Now I turned to DNA. The amount of DNA shared with matches was about right for Anne as a daughter of Martin. But there can be quite a bit of variation in inherited DNA, so I was not comfortable placing Anne in this tree based simply on shared DNA. Yet. So I constructed the following chart. It requires some explanation.

Hayden DNA Comparison Chart

I identified fourteen DNA matches to my parent on 23andMe who were likely related through the Haydens. Of these, I could place ten on a Hayden family tree. In the chart above I recorded in the lower half the relationships between all these cousins as read from the tree and added average amount of DNA that should be shared between these cousins, if only a simple single relationship exists. 3c-2/0.2 , for instance, is third cousin twice removed, who share an average of 0.2% of their DNA. The four empty lines are the four persons whom I could not place in the tree, and so with whom I cannot know their relationship with the others. In the upper half I recorded the estimated relationship and the measured amount of shared DNA as reported by 23andMe. The columns/rows of x's are Hayden descendants whose DNA was either not analyzed on 23andME or who did not show as a match to my parent. The gray boxes are where DNA matches were not detected/reported, even though both were matches to my parent. Finally, I color coded the results. Basically, green shows 23andMe estimates close to true relationships, "red" (purple) not close, and yellow somewhere in between.

First I compared just the matches among themselves. Now I'm down to eight matches: started with fourteen, four I couldn't place in the tree and two did not show up as a match to my parent. Among these eight persons, there are twenty-eight relationships. Of this twenty-eight, eleven (39%) don't show up at all. This is typical for 3rd/4th cousins. Of the seventeen that do appear, eight (47%) are good/green, six (35%) are so-so, and three (18%) are incorrect. Note that by "incorrect" I mean percent shared DNA is different from what I expect by a factor of two or more. This is only half a generation, or, say, the difference between 4c and 4c-1 (fourth cousin vs. fourth cousin once removed). This may not be a huge error, but it is important in determining where Anne might fit into this tree. So the above numbers, % good numbers, are my baseline.

Now I look just at my parent's relationship with the other eight. In order to have relationships from the tree, I have to place her somewhere in the tree. I placed her as a child of Martin and Katherine. There are eight possible relationships. Of these, none did not show up. That's obvious, because those that don't show up are not visible in my results. Actually, I later discovered that one of the persons who did not show has had her DNA tested on 23andMe, but can't find me among her matches, either. Of the eight that are visible, 50% are green, 37.5% are yellow, and 12.5% are "red". I think these compare very well with the 47%, 35% and 18% baseline. My conclusion is that my ancestor, Anne Hayden Campbell, is the daughter of Martin and Katherine Headen.

Now I need to go back and fill in all those quick-and-dirty sources I noted while assembling a family tree ...

Evolving Genealogy Strategies and Successes

It has been frustrating tracing the Cushing family back beyond what we already know. In all fairness, we began by knowing a lot, since one of my uncles recorded the family genealogy in about 1931 in a  document untitled "Family History (Exclusive of Darwin's Age of Monkey)". My parents, my sister, and some cousins have travelled to the town and visited the church where many of Cussen family was baptized and where Dennis Cussen and Katherine Casey were married. One of the great milestones in American genealogy research is locating a family prior to emigration, and with this family we were fortunately handed that information before beginning our research.

Now, though, finding more information about the Cussen and Casey families is very difficult. There are very few records from the early 1800s and earlier. It could be that Dennis' father was a Francis Cushen who worked land in the Galbally area, but I haven't spent much time pursuing this because tithe applotment books do not list family members. Church records are rare before about 1825, so I've been unable to research there, either.

My principal strategy for extending the family backwards has been to publicly publish what I know about the family and to seek out genealogists in other branches of the family through which more information may have been preserved. While this has not extended my tree back in time, it has been very productive. Dennis and Catherine had about thirteen children. At the time I began my research, we knew descendants of only one other branch of the family. Of the remaining eleven children, three disappeared (appeared in only one record at some point) and one died unmarried at the age of 22. So that left seven branches of the family, perhaps some who had stayed in Wisconsin, to search for. Through the Internet, especially through message boards like Rootsweb and Genforum, I was able to contact four more branches. It turns out that one of the remaining branches left no children, hence no descendant genealogists, and the remaining two were women, for whom tracing marriages and name changes and moves can be very difficult. I was finally able to track the last two branches about two years ago. During all of this, we were able to share our respective genealogies and learn about the spread of the family. A disappointment for me, though, was that there was no documentation about our family prior to our Age of Monkey.

A second strategy I attempted was a search for Caseys. It turns out that a Casey family lived on the farm adjacent to the Cussen/Cushing family in Fort Winnebago in about 1850. I researched this Casey family and found that they had emigrated from Ireland at about the same time as the Cushings, that there was another closely related Casey family that also lived, albeit briefly, in Fort Winnebago, and that the Casey fathers, Patrick and James, were both just a few years older than our Katherine Casey Cussen. I thought there was a good chance these three were siblings. In the years since, however, I have found no evidence of a family connection. Meanwhile, with the explosion of paid membership-based genealogy services, especially ancestry.com, genealogy research has gone largely behind walls and I have made no contacts with the Casey family that I researched in and from Fort Winnebago.

Now, a new strategy has emerged: DNA. I've been researching DNA genealogy for about a year and a half, now, with disappointingly little to show for it. Perhaps that's too overstated. I feel that given the enormous amount of work I've put into DNA research, I should have more to show for it. But I see that I actually have made significant progress in several branches of the tree.

Yesterday, I was able to connect a DNA match back to one of the Fort Winnebago Casey families, one of my most important goals in my DNA genealogy research! The amount of shared DNA makes is very likely that Patrick Casey was indeed a brother to Katherine Casey Cussen. I was more confident of a close relationship between the two Casey men, since they were living together at one time, so James Casey is probably also a sibling. This gives me enormous incentive to start searching through online baptismal records at the National Library of Ireland to locate these Casey families. The kids were mostly born in Ireland in the late 1820s through early 1840s, and baptismal records were widely available.

My Love Hate Relationship with Ancestry.com, continued

I have a few relationships with Ancestry.com. My earliest is my use of the Rootsweb pages, message boards and WorldConnect family tree. At some point, Rootsweb was acquired by Ancestry and I had to set up an ancestry account to post messages and update my tree. Occasionally, I have tried a trial membership of Ancestry's data service, but since I have a pretty well-developed family tree I find that within the trial period I find the small amounts of additional information related to my own family. More recently, I manage some dna test kits for a relative using AncestryDNA. I've made some family connections there, but am hampered by not being an Ancestry subscriber, and so not having access to family trees that are linked to the dna matches.

So two new factors to add to my thoughts about Ancestry.com . The first relates to the Rootsweb WorldConnect trees. Ancestry has just reworked this service. Apparently, many Ancestry.com subcribers also had Rootsweb accounts and used the same passwords for both. Since Rootsweb is over 20 years old, it apparently was easy to hack into and someone did, thereby gaining access to a bunch of Ancestry account passwords. So Rootsweb was shut down, with bits and pieces coming back online as they become secure. What's the point? I (and others who use the Rootsweb WorldConnect family tree) have been unable to update our trees in about two years, while Ancestry updates the underlying software. Which has finally been done. Now, however, by posting a tree, it is no longer mine. Technically, it's mine, but Ancestry users may attach any parts of it - up to it's entirety, I assume - to their own family trees, which then becomes theirs. I realize that I have no copyright to the information itself, but I was okay with making information available to people to copy - more or less manually - if they were interested enough to do that. I'm not ready to provide for free to a paid service 25 years of research that can be copied at the click of a button. So I'm looking for some other way place to make my tree publicly available, but under my own control.

But on the Love side of the equation - which doesn't often happen between me and Ancestry - they are testing a Beta version of a dna matching service. It now gives me limited access to trees associated with the dna kits, allowing me to find a match to my own family tree. This is a huge improvement in the usefulness of AncestryDNA. I would now recommend AncestryDNA for anyone seriously researching their genealogy. (MyHeritage also allows trees to be attached to dna kits. 23andMe does not, though they do provide some other helpful information.)

P.S.: I completely understand how useful and valuable Ancestry is for many people. In many ways, it's just not right for me. Except for the new Beta version of AncestryDNA ...

My Genetic Genealogy: Third Party Software

There are a number of programs available to assist with DNA genealogy research. So far I've tried two: Genome Mate Pro and AncestryDNA Helper. I stumbled upon both of them. I suppose I should find a good DNA genealogy group to join where they probably talk about such things.

Genome Mate Pro

Genome Mate Pro allows you to manage and explore your matches from your DNA analysis service. Many (most?) services allow you to download a file of your DNA matches that includes names and the portion of DNA in common. You have this information available through your service online, but there are advantages to using GMP. If you are using more than one DNA analysis, either from different services or for different individuals, you can display them all together in GMP. That allows me to take notes, list relationships, see whose been identified, etc. in one list, using one database. Adding a GEDCOM file (a genealogy file that includes all your known ancestors) makes it easier to associate DNA fragments with your ancestors, and to see together those who share those fragments, no matter which service tested them. There are lots of other convenient features, too. The hope is that if I can identify enough closer cousins, and their DNA fragments, I can start to see patterns in DNA segments that will lead me to identifying ancestors farther back than I have been able to do following paper trails alone. By collaborating with people that you know are related to you, through DNA matches, your search becomes much more focused.

AncestryDNA

Now I would like to use this software to analyze and track DNA matches made through a relative on AncestryDNA. Ancestry has by far the largest number of DNA kits - persons who have submitted their DNA to Ancestry for analysis - in their database. I am constantly thwarted in my attempts to glean useful information related to the DNA matches because all of the useful information - family trees, in particular - is part of the paid Ancestry subscription service which, starting at $200 per year, is way too expensive for me. In the same vein, AncestryDNA does not allow the downloading of DNA match data. The DNA is yours, but the matches are part of their service and if you want to use them to have to do it through them. Note: I am not complaining. That's just the way it is. The other companies would like to be in this position, I'm sure, but they're not, and to chip away at AncestryDNA's market share they offer match sharing files.

AncestryDNA Helper

There are a number of third party apps to try to get around the Ancestry block. I've only tried one so far, AncestryDNA Helper. It is an extension added to only the Chrome browser. I tried it a couple of times, but it or Chrome freezes up, and I don't get all the data. There are lots of resources on the Internet that give you all sorts of ways to try to successfully complete the data harvesting. There are lots of people who give very high marks for the software, so your experience may be better than mine. There are also lots of people who talk about the software freezing up and alternatives that work better, perhaps with a paid subscription. Personally, I'm new enough to DNA genealogy research that I have lots of non-Ancestry families to work with and don't want to put the time into this software to see if I can get it to work. If it does work, it still will not have DNA fragment. I believe I could hope for a list of names, estimated relationships, and amount of shared DNA (percent and cMs). So I could use the research management part Genome Mate Pro, but not the DNA comparison parts.

Or Download Upload Download Read

Another alternative is to download your raw DNA file from AncestryDNA, upload this file to another DNA analysis service - I've seen GEDMatch, MyHeritage, and FTDNA mentioned - where matches will be made with this new services database of participants, then download a matches file to your computer and, finally, read this file into GMP for tracking and analysis. I'm not recommending or dissuading you from doing this. I, personally, have not gotten over my privacy concerns about shared DNA and, though I've participated in a service, I am reluctant to make my DNA even more public by sharing with additional services. Personal choice. I may change my mind next month.

DNA: Case Study: Margaret Connery Lardner

Beginning

One of my first ventures into DNA genealogy  began by simply selecting a name from the list of DNA matches that was the same as one of our ancestors, in this case McLaughlin. In reply to my query, I was told that McLaughlin was a married name and that the DNA match had no genetic connection to that name. Oops! Note that this is not like picking a name off the Internet somewhere and searching for a connection. Because this individual was on a list of DNA matches, a relationship was certain. I was just looking in the wrong direction.

Redirect

Taking a closer look at a list of DNA matches that we had in common, it seemed our connection was in a cluster of Irish immigrant families in Ontario, Canada in the mid-1800s. So I proposed those names - Connery, Pyne, Miller, Roche, Hawes, Chappel. I also noticed from our matches-in-common list, that some of the others were more closely related to my counterpart than she was to us - 3rd cousins instead of 4th cousins. Thinking she might have already had contact with some of these relatives, I sent her some of those names or Ancestry "handles". (Handle, screen name, member id, ... The designation clients choose to show as their identity. To guard privacy, many are cryptic.)

Two heads are better

No luck on the names in my family tree. But she did know that one of the "handles" I mentioned was related through a Lardner family. No Lardners in my tree, but this turned out to be the clue that led to finding all the pieces of the puzzle.

At this point I just started trying combinations of information in search engines to see what might pop up. Lardner and born in Ontario, Canada, or Ireland, or New York. Google, FamilySearch, and Rootsweb's WorldConnect family tree. (I don't have a paid subscription to any genealogy research companies, like Ancestry.com, so only use publicly available resources. Occasionally, I'll use paid services available through my library.) Lots of useless results. Knowing that some of our Ontario ancestors migrated across the border to the Buffalo, New York area, I tried that as well. WorldConnect gave a list of Lardners, one of whom had married a Conroy. Recognizing that Conroy is not far from Connery, I started gathering information on that family.

Searching my family tree

The couple that I had found were Thomas Lardner, born 1852 in New York, and Margaret Conroy, born 1852 in Canada. In my family tree was a Margaret Connery, born to Michael Connery and Ellen Roche in Ontario in about 1855. But I had found no information on our Margaret after the 1861 census in Ontario.

Armed with names and dates and birthplaces, FamilySearch provided many more records. The family lived mostly in Lockport, Niagara county, New York. The earliest record I found was in Ridgeway, Orleans co., adjacent to Niagara county. This also happens to be where our Pyne ancestors moved after leaving Ontario. In 1870, the Pynes had a Conroy couple living with them - Richard and Ann, born 1851 and 1852, respectively, in New York. It was time to go back and look at my Connery family and try to make all of this fit together.

The story

After reviewing the research I had on our Pyne and Connery ancestors, now viewing this Richard Conroy guest as a possible Connery relative, I concluded that this is their story:

Michael and Ellen Roche Connery immigrated to Lindsay, Victoria county, Ontario, Canada in about 1840 with their two young daughters, 4 year old Nora and 2 year old Mary. They had at least four more children in Canada, born between 1845 and 1859: James (1845), Michael (born 1848 and probably died before 1861), Richard (1849), and Margaret (1852). Nora married John Pyne, son of James and Catherine Miller Pyne, who had immigrated to Lindsay in the 1830s. I couldn't find Michael and Ellen Connery after the 1861 census, and believe they passed away in the 1860s.

Possibly after the death of her parents, in about 1870 Nora Connery Pyne emigrated with her husband and three children, to Orleans county, New York. Two of her younger siblings, Richard and Margaret Ann, came with them. (I had originally thought that Richard and Ann Conroy were a married couple, and had not realized they were family.) Two years later, Margaret married Thomas Lardner. Thomas was a mason, as was John Pyne, so perhaps they met through John's work. They had six children born between 1874 and 1896: Martin (aka Mark), Aggie, Thomas, Carrie, Roswell and Marie.

Connecting us

When I collaborate with someone or have contact with a relative, I try to place them in my family. So now I set about he work of connecting Margaret Connery/Conroy Lardner circa 1875 to one of descendants in 2018. Not wanting to find all of Margaret's descendants (too much work), I went back to searching for obituaries naming our new cousin, then following leads back to census records, marriage records, grave sites, etc. In this case, we (she and an in-law, actually) are 4th cousins, correctly estimated by Ancestry.com .

DNA: Case Study: William Sorrance Covington

Background

So far, the typical meeting between me and a DNA match consists of my choosing someone not too distantly related - a 3rd or 4th cousin - and sending them note, suggesting a related family based on common matches I've already identified, and asking if they know how we might be related. In this case, my match knew only her mother's name, having had no contact with family that had been in Oklahoma. Not a lot to go on.

Start by finding an obituary

In this case I was able to find a recent obituary naming my match. In the obituary were also birth dates and places, maiden names, and the names of both parents - Earl Shotwell and Bell Covington. This lead to locating the family in Fresno, California in 1940 and in Oklahoma in 1930. Earl and Bell must have married in the late 1920s. Their first three children were born there, then the family moved to California in about 1936. Belle's mother, Lucinda, died in Texas in 1936 and I've wondered if this had anything to do with the departure of the Shotwells. More likely, they were just part of the large migration from economically depressed Oklahoma to the opportunities in California. (See this article on the migration from the Oklahoma Historical Society: http://www.okhistory.org/publications/enc/entry.php?entry=OK008 .) (On a personal note: in the late 1970s, while working for a PG&E road crew, I was amazed to hear a colleague's southern accent, which he explained as him being from Modesto, in California's Central Valley. He had no idea what accent I was talking about. I later learned about the large migrations from Oklahoma and other southern states to the Central Valley.) Chasing Bell back even further in the census records, she was the second of seventeen children born to William Sorrance Covington and Lucinda Titsworth, a family that seemed to move back and forth between Oklahoma and Texas. William and Lucinda were married in the Indian Territory, in or near the Kiowa nation.

Who is William Sorrance Covington?

I still haven't completely figured out William Sorrance Covington. The DNA match seemed to indicate a Covington connection, so my focus was on just this family line. Later census records say William was born in Oklahoma or Texas circa 1873. Earlier records (1900 and 1910 censuses) say he was born in Arkansas. Finding William prior to his marriage in the Indian Territory in 1899 has been difficult. There is a 20 year census gap between 1880 and 1900. Still, I should be able to find him in the 1880 census. But haven't been able to.

Ancestry.com estimates that the two DNA matches are fourth cousins, or back five generations. This should be in my known family tree. Taking another look at my tree, there is a William Covington born in 1870 in Arkansas to our ancestor, James Mattis Covington, and his second wife, Winnie Watson. This William would be a 1/2 brother to our ancestor, James. If William Sorrance Covington is, indeed, our William, son of James, the relationship between the two DNA matches is 1/2 second cousin twice removed. The amount of shared DNA expected for this relationship is about midway between a third and a fourth cousin. I'm a DNA novice, and don't know the proprietary criteria that Ancestry.com use to estimate relationship, but midway between 3rd and 4th is at least close to the predicted 4th cousin, indicating that it is at least plausible that William Sorrance is a son of James. I have not yet attached William Sorrance to my tree, but likely will soon.

DNA: Case studies

I'm going to be publishing articles about my genealogy research through DNA testing. These articles may be more verbose than previous articles because my intent is to demonstrate how I am using the results of DNA testing.

The DNA matching services (I've used Ancestry.com, MyHeritage.com, and 23andMe.com) analyze DNA, compare it with others' DNA samples and identify which segments of you have in common with the others. From this, they quantify quantity of common DNA and the length of the segments in common and apply their proprietary algorithms to estimate your relationships with others. They present you with a list (about 1000 from 23andMe, about 3000 from MyHeritage; more is not necessarily better) of persons with DNA matches in default order of how closely related they predict you are. There are some capabilities for attaching family trees or lists of surnames or family origins, etc. to allow for some searching.

Contacts

So the first, and arguably most important, use of DNA analysis is that you get a list of likely related persons and a means to contact them (usually internal messaging). You can sometimes take advantage of searching through family surnames and trees, but I find that most people don't contribute this information. It's easy to contact your new-found relatives and ask about connections, though less than half seem to reply. Still, the first use of DNA analysis is to identify relatives with whom you might collaborate and find common relatives.

DNA map

The second use requires some calibration. By identifying your closest relatives you can begin to associate segments of DNA with ancestral lines of your family. This is so much easier to do with first and second cousins. If you've done lots of research and have a well-developed family tree, third cousins can be found without too much trouble. With more distant relatives, if you can find the connection, the segments in common can be used to add a great deal of precision to your map of inherited DNA. But these more distant connections are generally very hard to establish. In any case, the second use of DNA analysis is identifying DNA segments that belong to ancestors. This in turn helps to focus your search for a common ancestor on certain families, avoiding impossible amounts of time spent researching and eliminating family lines.

By the way, to keep track of DNA segments and compare them and to keep track of the status of my investigations, I use a third party software called Genome Mate Pro ( https://www.getgmp.com/ ). Doesn't have the flash and polish of a Microsoft product, but it serves it's very basic (but complicated) purpose very well. You export your DNA analysis from the testing service, then import it into GMP. Results from different services and individuals can be displayed side by side, as if they all came from one service. I'm a novice at this, am still trying to figure out the best way to use the DNA information, and have not yet reached any huge insights or made any huge discoveries. So far it seems to be a lot of work, just using different tools and modified processes.

Relationship estimates

The third use is a confidence measure. Each DNA match is labeled with an estimate of the relationship, or a range of relationships. It's useful to understand some basic DNA math. Find "DNA" in the word cloud on this blog to read more about that. The most important thing is to understand all the halves and halve nots. Off the top of my head, some are:

1) When referring to the DNA of a common ancestor, each subsequent generation inherits about half as much DNA as their parent has. So a great-grandchild has half as much as a grandchild. Your first cousin once removed (child of your first cousin) has only about half as shared DNA in common with you as your first cousin. When you put these two examples together, second cousins (each of whom has just 1/2 half as much of their ancestors DNA as their parents) have about 1/4 as much shared DNA as their first cousin parents. Etc.
2) For this same reason, each "removed" in a relationship cuts the amount of shared DNA by 1/2.
3) You inherit about 1/2 of your DNA from each parent. About 1/2 of my DNA is.  from my mom; about 1/2 is from my dad. This is important for step- or 1/2- relationships. Suppose your maternal grandparents divorced and remarried. Consider a first cousin who is a grandchild, like you, of your maternal grandfather, but your maternal grandmother's were different. Since any DNA you share with this 1/2 first cousin came only from your maternal grandfather, but none is shared by you from your maternal grandmothers, a 1/2 first cousin will only share half as much DNA from grandparents as first cousins who share both their maternal grandmother and grandfather.
4) Siblings are a little trickier. You and your sibling each inherit 1/2 of your DNA from each parent. But it isn't usually the same half. So even though you both get your genes from the same source, on average you share about 1/2 of the same DNA as a sibling.

A bag of marbles, anyone?

This can be confusing, especially if you're math-phobic. Do I need to say anymore? If you're lost, think of DNA like a bag of marbles. Each of the marbles - cat-eye? - has a different color. One bag of marbles is your mom's DNA, one is your dad's. To get your DNA mix, you scoop out half of your dad's marbles and half of your mom's and put them in your marble bag. About half (maybe exactly in this case) of your marbles come form mom, half from dad. You do the same thing for your sister. (But first you have to replace all the marbles you took out.) After you scoop half of mom's marbles and half of dad's into your sister's bag, you'll find that half of your sister's marbles are from you mom and half are from your dad. But if you compare which marbles you each got from your parents, you'll find they're not the same marbles. You'll find that about 1/2 of the marbles you got from your mom are the same as ones your sister got, but that about 1/2 of what you got does not match what your sister got. In fact, if you have several siblings, you'll find that collection of marbles you have are all different. Some of the marbles are the same, some are different, and the mix is different for each sibling. The exception is for identical twins. There you each got the exact same marbles from each parent, and you share 100% of your DNA with your identical twin. That is my "halve not":

5) Identical twins/triplets/etc. have the same DNA.

Relationship estimates continued

This brings me to my fourth use of DNA analysis. Sometimes you come up with the relatives that make up a new branch of your family tree. I'll call this "my claimed relationship" (as opposed to the DNA service's "estimated relationship"). You can compare shared DNA for your claimed relationship with the amount shared in the estimated relationship. It should be approximately the same. An example: Ancestry.com claimed a relationship of 4th cousin for a recent pairing. When I came up with what I thought was the new family tree, my genealogy software told me my claimed relationship was 1/2 third cousin once removed. Ouch! Start from 3rd cousin. Rule 3, above, says cut shared DNA in half because of the "1/2", meaning that the two persons were descended from step siblings. Rule 2 says cut it in half again for the "once removed". Now I've cut shared DNA to 1/4 compared to third cousins. Rule 1, above, says 4th cousins share 1/4 as much DNA from a common ancestor as their third cousin parents. In other words, 4th cousins share the same amount of DNA as 1/2 3rd cousins once removed, so Ancestry's estimate supports my claim.

Recap

Articles about DNA case studies may be a little wordier to show what's involved in conducting DNA-assisted genealogy. I've so far found DNA analysis to be useful in (1) identifying relatives which whom I can collaborate to find our common ancestor, (2) helping associate DNA segments with specific grandparents to help focus our efforts in finding a common ancestor, (3) and providing a relationship estimate that might be used to validate the plausibility of my claimed relationship.