DNA, CSI, WTF?Jul 10th, 2009 | By Leonard Legends & Legacies | Category: How-To
DNA testing, if you believe the hype, is one of the hottest things going in family history/genealogy today. I’ve been approached more than once about contributing a sample to one database or another. So I finally decided to look into it. Guess what I found.
First off, you all know that the DNA “science” we see on the sixteen versions of CSI/Law and Order is mostly crap, right? You won’t get your results in half an hour, they won’t tell you whodunnit, and the chances of finding a long-lost relative are practically nil. What you might discover, is whether you and another donor might have a common ancestor.
One thing TV gets right once in a while, is the fact that DNA results are only useful if you have something with which to compare them. Find someone with similar genes, and you might be able to determine your Most Recent Common Ancestor (MRCA). And in order to do that, the two of you have to do the research! No such thing as a free lunch, right?
I won’t go into the dirty details of genes, genomes, haplogroups and markers… except to say there are basically three types of DNA tests. One compares male genes to male genes, another compares female to female or male, and a third ignores gender altogether and compares ethnic markers for a really big picture. The more markers you test for, the more expensive the test… individually priced for your convenience.
The Y-DNA test only applies to males, since they’re the only ones blessed with a Y chromosome. In this case, us guys can compare genes to any other male, preferably someone with the same surname. (There’s a measurement joke in there, and I’m just going to leave it.) If there are similarities, the test will estimate how far back we have to go to find a common ancestor. It’s usually accurate within a generation or two, but can’t indicate specifically who the ancestor might be. So we’re back to research again.
The mtDNA or Mitochondrial DNA test is the female equivalent of the Y-DNA test, with a twist. Mothers, you see, contribute Mitochondrial DNA to their offspring, both male AND female. The twist is this… ONLY females can pass it along to the next generation. Therefore, an mtDNA test on ME would confirm my mother’s identity (assuming I had her sample, too), but the same test performed on my son would provide NO indication who either of his grandmothers were. The same test done on two women could tell them if they are related, but because ALL women pass along their mtDNA, the estimate of Most Recent Common Ancestor could be off by a thousand years! Crap. Back to the research.
Last but not least, autosomal DNA tests compare non-sex chromosomes to look for ethnic similarities. I already know my ancestors originated in northern Europe, so it probably wouldn’t tell me much else.
So here’s the deal… if you’re primarily tracing one surname, Y-DNA is the way to go. Ladies, you’ll have to ask your father or brother to contribute for you. If we compare two men with the same surname, assumed to be closely related, and they do NOT match… we have what’s euphemistically called “a non-paternal event.” *snicker* It happens, and not that infrequently.
No such complications with the mtDNA test, unless there was a serious mistake at the hospital. We can trace a whole long line of grandmothers with mtDNA, but the test can’t tell us their order of birth. Damn. Back to the research again.
The jury is still out on autosomal DNA tests, but the bottom line is, it’ll cost you a bundle to find out your grandmother was one-sixteenth Cherokee and even then it won’t tell you which grandmother.
I’m running long and I apologize, but it’s a complex decision, whether to test or not. And I haven’t even touched on privacy concerns, lab credibility, or competing companies. There are essentially two major players in the DNA-genealogy field right now. Family Tree DNA got the jump on Ancestry.com DNA by a couple of years and therefore has a slightly larger database with which to compare. Ancestry.com is cutting prices and I suspect the two companies will be head-to-head in very short order.
Will I contribute? Probably. We’ll see. I’m leaning toward Ancestry’s $79 Y-DNA test. Unless, of course, Family Tree wants to make me a better offer.