Skeptical? DNA Doesn’t Lie.

So, what did it mean?

50.0% shared, 23 segments

23andMe tests autosomal DNA. To break it down as simply as possible (I’m not a scientist and most of what I’ve read about DNA and genetics goes right over my head, so it helps me to keep it simple), the majority of our DNA is autosomal DNA. An autosome refers to numbered chromosomes, as opposed to the sex chromosomes. We all have 22 pairs of autosomes and one pair of sex chromosomes (the X chromosome and the Y chromosome).

The examination of one’s autosomal DNA is highly useful for genealogical purposes. If you share identical segments of DNA with another person, you share a recent common ancestor. The length and number of these identical segments will predict how close the relationship is. The more autosomal DNA that you have in common with another person, the more closely related you are.

A child receives 47-50% of their autosomal DNA from each of their parents, and similarly on average a child receives about 25% of his autosomal DNA from each of his four grandparents. The chromosomes recombine, or mix, as they are passed down from parent to child, so the size of possible shared segments gets successively smaller with each generation.

So check this out:

50% Mother, father, siblings
25% Grandfathers, grandmothers, aunts, uncles, half-siblings, double first cousins
12.5% Great-grandparents, first cousins, great-uncles, great-aunts, half-aunts/uncles, half-nephews/nieces
6.25% First cousins once removed, half first cousins
3.125% Second cousins, first cousins twice removed
1.563% Second cousins once removed
0.781% Third cousins, second cousins twice removed
0.391% Third cousins once removed
0.195% Fourth cousins
0.0977% Fourth cousins once removed
0.0488% Fifth cousins
0.0244 Fifth cousins once removed
0.0122% Sixth cousins
0.0061% Sixth cousins once removed
0.00305% Seventh cousins
0.001525% Seventh cousins once removed
0.000763% Eighth cousins

(Data from International Society of Genetic Genealogy.)

If you are wading through the vast sea of DNA testing to aid your search, I would recommend reading author and adoptee, Richard Hill‘s website, guide and book, Finding Family.  His story is nothing short of amazing.  He searched for decades and finally found answers through DNA testing.  His results were not at straightforward as mine in the beginning–an adventure for sure. He started his DNA search when the science was just starting to evolve and he followed it through its evolution, using all of the available testing sites and sorting through all of the available information.  Mr. Hill has generously compiled all of the useful and invaluable information and has made it available to anyone who is searching.  For free.

I spent an entire weekend researching and trying to figure out what “50%, 23 segments” meant (thank you technology and Richard Hill!).  I was convinced that the Father that 23andMe found was my biological father.  Was he convinced?  Not so much.

12 thoughts on “Skeptical? DNA Doesn’t Lie.

  1. So sorry to hear that. Well, if he wants convincing, you could always offer to do a paternity test with him. Never mind that 23andme is a MUCH better and more comprehensive test. Some people only trust what they already know. Unless he has an identical twin, 50% match means he’s your biological dad, no matter what he wants to be true. I don’t know the nature of his communication to you but I’m hoping he’s just getting used to the idea and will come around.

    • Thank you, Cyndi! Thanks for reading. We’re communicating, but the connection is so twisted and the story is 50 years old . . . I, too, believe that the DNA doesn’t lie, but I think he needs some convincing.

    • Thank you, Traci! It took many years for me to work up the courage to uncover my truth! It’s a story that is still evolving . . . I’ve learned to be hopeful, but it’s not always a happy ending. 😉 The truth is what matters.

  2. You are right! The truth isn’t always a happy ending but what matters are the answers you are in search of. Be proud of yourself for what you have become and accomplished. 🙂

    My story is different. I did DNA testing to help develop my family tree and found out that my father isn’t my father. I never had a clue! I’ve dealt with rejection from 1/2 siblings.

    I’m anxious to hear how your story unfolds and can only hope that your biological father (DNA doesn’t lie), sees what a wonderful person you turned out to be. Thanks for sharing with all of us!

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