dna-tree.gifNo question about it, genetic genealogy — the hobby of using genetic tests to trace your ancestry and, in some cases, to locate previously unknown relatives — is hot these days. Today, of course, brought the news that Ancestry.com, a genealogy Web site that lets users construct family trees and pore over digitized versions of old census records or ship-passenger manifests, is launching a DNA Ancestry service as well. (Matt covered that in his story this morning over at VentureBeat proper.)

But the Ancestry.com move is really just the latest sign of a growing groundswell of enthusiasm — and, of course, hype — over new ways to buttress old-fashioned genealogy research with what seems to be cold, hard science. DNA Direct, which sells various medical genetic tests directly to consumers, just began offering genealogy and “ethnicity” tests as well, “in response to customer requests.” Startups like 23andMe plan to make genealogy searches and genome-based “social networking” a key part of their business (see our coverage here and here). 60 Minutes just ran a lengthy segment on genetic genealogy that purported to puncture some of the hype in the field (much to the dismay of some).

There’s no particular harm in any of this that I can see, which is a good thing given that I’m not sure what anyone could do about it if there was. (Again, the technology is getting ever cheaper and more available, so this train is pretty much leaving the station whether we like it or not.) Like anything else, of course, you should probably have a good sense of what you’re getting into before you start forking over hundreds of dollars for genetics tests. It’s important to remember that the tests often only suggest relatedness without really proving it, particularly where distant relatives are concerned. And of course anyone sending in a cheek swab or a saliva sample for a genetic test should be braced for the possibility of an unexpected family surprise or two, particularly once you begin comparing your genes with those of your (purported) relatives.

Mostly, in fact, the explosion of interest in genetic genealogy strikes me as an interesting example of what happens when a new technology — here, relatively cheap and available genetic tests — that appears to offer rigor and certainty meets a social phenomenon such as genealogy (the U.K.’s Guardian newspaper claims tracing your roots is the second most popular hobby in the U.S., after gardening). Without question, there will be some hurt feelings and deflated hopes as people realize that genetic testing has its limitations, too.

It’s also a nice illustration of the sort of weirdness we’re all going to face as our genetic information becomes more transparent to us and forces us to redraw many mental categories that don’t map particularly well onto the genome. The Guardian, for instance, recently ran this great story that looked into what genetic testing says about our sense of identity, particularly when the tests turn up unexpected results related to ethnicity or paternity.

Also, as I’ve noted before, there’s also the fact that your DNA probably isn’t anywhere near as private as you’d like to think, given the fact that you shed DNA-containing hair and skin cells pretty much wherever you go. That notion was underscored by this creepy story from the NYT back in April about DNA scavengers who, by hook or by crook, aim to get and test genetic samples from people they think might be related to them. And at that, I’m pretty sure we’re still only just scratching the surface of other changes that are in store for us.

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