Tuesday, February 14, 2012

Is Your Family Tree Broken?

   Non-paternal events (NPE).  There, I’ve said it.  Just how often has it happened in your ancestry?

   Who’s your daddy?  Non-paternal events include – illegitimate births, cuckoldry, sperm donations, hidden adoptions and the use of an alias or intentional name changes.

   The average percentage of non-paternal events if often quoted as 10%.  If you search on the topic, you will find that studies show that 10% is too high.  Keep searching and you will find that in some cultures that number is too low.  Let’s consider the fact that these studies are current day populations and may not represent our ancestors of the last 10 to 20 generations.  These studies also focus on illegitimate or adulterous births.  If we add the events that include adoptions and intentional name changes then 10% is probably safe to use for this illustration.

   Let’s look at your ancestry (or mine) for the last 10 generations.  That is a group of 2046 people, all of them are your direct ancestors.  1023 couples that then gave birth to the next generation.  If we use 10% for NPE, then 102 of those children are not related to those fathers or don’t carry the same surname as their paternal grandfather.   102 of your gggg…grandparents are not genetically connected to their surname.

   If you have done a terrific job of researching your family tree and have the documented birth records for everyone then 10% of the time all you have is a piece of paper.  Your beautiful family tree could just be a pile of fragmented twigs and branches with no relation.  Even if we use an ultra-conservative number like 1% we would still have 10 breaks.  Print out your tree and randomly cut it into 10 pieces.  The piece with your name on it is probably still valid.

   I can hear you now, at least those of you who have stopped crying.  You’re saying, “Ok, I get it, I get it. So, what do I do now?”

   The sands of time have erased everything except your DNA.

   Only through DNA testing, can we ever know for certain that our genealogies are real and not a piece of fiction.  We need to use all the available test types – y-DNA, mitochondrial DNA and autosomal DNA.
If you are male, you are in luck.  You can get all three tests.  If you are female, you can get the mitochondrial and autosomal tests.  Ladies, don’t stop there.  Get your father’s or your brother’s y-DNA.

   To do this right you will need DNA samples for every surname in your tree.  That will not be physically possible.

   Here is a method that will get you many of the surnames.  Naturally, start with your own surname.   Most of us focus on our own immediate surname.  Get dad’s y-DNA and check it against the half dozen DNA databases available and the first thing that you will hopefully find is other folk with the same surname.  Bingo, we have a winner.  My wife’s surname, Clark, has a solid genetic (and paper) line back to 1621.  If I checked the databases and consistently got the surname Brown, then I’d know for certain that I have a break and I would start the process of figuring at which generation the break occurred.

   Let’s assume dad’s DNA went well.  Next get mom’s dad’s DNA and repeat the process.  If that’s not possible, no fear, get mom’s brother’s DNA or mom’s brother’s son or mom’s dad’s brother’s son.  You get the picture.  Here is the added instruction – don’t only get their y-DNA.  Get their autosomal DNA as well.  First, compare your autosomal with their autosomal.   Double check that cousin Bob is really genetically related.  You can’t be too safe with all those NPEs flying around.  Now cousin Bob’s y-DNA can be used to validate that surname.

   While the y-DNA is great for the surname check, don’t forget to use the mitochondrial to test against hidden adoptions.  Every woman in a maternal line should have nearly identical mt-DNA.  Find cousin Sue (you share a gg-grandma Polly) and check that you are related by both autosomal and mt-DNA.  Move out a generation and find cousin Berta (you share a ggg-grandma Molly [Polly’s mother]).  If the autosomal and mt-DNA don’t match then maybe Polly was adopted.

   You should be able to continue these methods with anyone you share a 5th or 6th great grandparent with.  That is 7 or 8 generations out of the 10 we started with (or about 254 surnames) that you could verify with DNA.  The limiting factors at this point are how far back in time the autosomal test will take you and the cost of each test needed.  DNA contributions of a distant ancestor are diluted with each generation.  The current autosomal tests will not get us any further.

   What the past will tell us about the future is that there will be newer DNA tests developed and the costs of existing tests will decrease.

   Start collecting DNA now.  It will only get easier.  Let’s work together to rebuild our broken family trees.

   Happy origin hunting.  


  1. That's great information. But I have a question.... I was adopted, I have no paternal male relatives to test. Our ancestral "brick wall" is the 2 generations prior to my paternal great grandmother. All the children in her generation & the one before her carry mothers name, no fathers on record. So is my case hopeless?

    1. I don't think your case is hopeless. Difficult? Yes. I am confused about your statement about being adopted and having a known paternal g-grandmother. There are autosomal testing techniques for folks that are adopted. I would be interested in learning more and help point you in the right direction.