As you delve deeper into your family history research, you'll soon discover there are endless ways to arrange your family tree. Learn more about the difference between a genealogical and a genetic family tree from one of our genetic genealogists.
“You have your mother’s eyes!”
“You look just like your grandfather.”
“You have your great-grandmother’s singing voice!”
Many of us grew up hearing sayings such as these, about how our physical traits, talents, or personality quirks remind family members of generations gone before us. For example, I’ve often been told that I must have inherited my love of music from my maternal great-grandmother, who was a talented pianist. However, I certainly did not inherit my paternal grandmother’s talent as a painter and artist – those skills must have gone to my cousins.
Using DNA to Create a Family Tree
As a genetic genealogist, I often think of the segments of DNA we inherit from our ancestors in the same way personality traits or areas of talent shine through across generations. Multiple descendants of a common ancestor all inherit slightly different portions of that shared ancestor’s DNA, just a person and their siblings may reflect different parts of their parent’s appearance as they age. There are traits we inherit and traits we do not.
Genealogical DNA tests are one of the many resources family historians rely on to solve complex problems. Every person inherits basically half of their DNA from their parents, about one quarter from their grandparents, one eighth from their great-grandparents, and so forth. However, this division becomes less even with every subsequent generation. After five or six generations, there may be ancestors from whom a person inherits no DNA at all.
In the following hypothetical genetic tree of a DNA tester, the first generation (“Joe”) shares 100 percent of their DNA with himself. Joe shares 50 percent of his DNA with his parent, but rather than an expected 25 percent shared DNA with each grandparent, Joe inherited a 21/29 percent split. At the great-grandparent level, each contributed 10 and 11 percent DNA, respectively. Notice how the sum of the DNA from the great-grandparents equals the total of their child, the tester’s grandparent.
This tester therefore could not share DNA with any descendants of his depicted great-great-great-grandfather’s ancestors. If the tester has genetic cousin matches to descendants of his great-great-great-grandparents, all shared DNA would be from the great-great-great-grandmother. If Joe’s great-great-great-grandfather was a stubborn brick wall ancestor, no amount of searching Joe’s DNA matches would yield relevant cousins.
However, let’s say Joe has a sister, Susan. Even though Joe and Susan are full siblings, they inherited different portions of their shared ancestors’ DNA. Susan’s genetic tree might look like this:
Susan inherited six percent of her DNA from her and Joe’s mysterious great-great-great-grandfather, whereas Joe inherited no DNA from him! Susan could very well have key genetic matches on that ancestral line that could break down the family’s stubborn genealogical brick wall. However, if Joe had relied on his DNA results alone and not enlisted his sister to help with the research by taking a DNA test, he may never have found out why that ancestor seemed so elusive in his DNA.
This principle can be extrapolated across varying degrees of cousins. A person and their first cousins share a set of grandparents, but each cousin inherited different portions of their grandparents’ DNA, second cousins share great-grandparents, and each second cousins inherited different portions of their great-grandparents’ DNA, and so forth. This is why it is essential to analyze the DNA results of multiple descendants of a research subject where possible. You never know which cousin’s DNA holds the key to unlocking a longstanding family mystery!
If you'd like help analyzing and organizing your DNA test results to create your own accurate family tree, you can purchase a research project to work with our professional genetic genealogy team.
Does your great-grandmothers initials LCB I purposely left the middle initial out and added her 1st name, maiden name 2nd and 3rd her marriage name.
I almost forgot to add did she have a stage name or given a nickname l “Queen Bea?”
I recently found the entire Maternal GermanUkrainian line of my family already researched in great detail on Geneanet. Surprise! I’m 78 and worn out from getting the American maternal:paternal tree completed thru a LT pro (three $ 5000 projects), plus my own personal efforts, plus a genealogy relative who’s a buff ($3000). I have joined Geneanet, but don’t have the energy to tackle German/Russian writing. Plus Geneanet isn’t very user-friendly.
I wasn’t thrilled with the level of detail in my first three LT binders, to be honest. I’m equally interested in having research on my relatives who served in Rev.War, War of 1812, and Civil War. For that I’d want more narratives about those battles, not just boring dates and ranks..Sorta like DAR-applications type compilations, but with more human interest.
I’m liking the AI bios which Ancestry has started providing, although they aren’t literary classics, to say the least. The wave of the future…
I can talk to someone with experirnce:interest in these two areas if we can schedule a date and time to discuss.. Please send me a resume on two people with expertise in these two areas. Thanks!
Hello, Diane! We’d love to help you get through all of this. One of our team members will be reaching out to you shortly.
Have relationships on two of my main family trees. The tree that comes up for DNA matches tends not to be the main tree for that match therefore the family connection can be off at times by generations or by generation. Appear to have quite of number of connections crossing back and forth between my two main trees. Also my Indig- roots number appears to be very low as well as location is not fully accurate for the family info I have not including possible Acadian Indig connections. Which DNA family label should one use the closer or further?
Have administration over my husband DNA account. We have a copy of his father’s birth certificate. His grandmother was not able to read or write, so information was recorded by someone else. The errored on the last names. The have the grandmother’s name as last name rather than his paternal father’s name. With the DNA: his cousin who’s father was our father’s brother carried the correct last name- but DNA has her listed as stepcousin. When they are full-blooded 1st cousins. There is also another relationship recent presenting on his mother’s side that with checking back with the names on both trees appear to be further back with another family member and not one they believe to related to as DNA proves out more my theory that what they believe or have presented (as the mother wasn’t married and list husband as recently deleted when baptised). What to do when errors made on birth records etc.
Hello Christine! You’ve done so much good research on your own! This would be the perfect opportunity to schedule a 45-minute consultation with one of our DNA experts. You can schedule that here: http://www.LegacyTree.com/genealogy-consultaion