Personal genomics question: am I related to my 5th cousins?

There are some personal genomics questions I get over and over via email. I thought I would post an answer so that Google could pick it up.

One of them usually has do with if someone is “really” related to someone who comes up as a 5th cousin on a DTC service. What does “really” mean?

Graham Coop has done the formal work to show that it’s highly likely all our genealogies intersect some point in the recent past. Several years ago in his paper with Peter Ralph, The Geography of Recent Genetic Ancestry across Europe, they used genetic data to infer just how closely European lineages coalesced with each other over the past few thousand years.

So yes, you are related (though that doesn’t mean you have matching genetic segments).

But that’s not the question people are really asking about. They are asking, does this DNA match increase the probability that I’m somehow related to this person?

In general, I think not. For example, I regularly get queries from South Asians about distant matches with Europeans. Does this mean they are European? No. I think what it means is:

1) There are lots of Europeans in the database, so a false positive match is likely to be European, even if you are non-European.

2) At short genetic distances, the segments are really mostly some sort of false positive.

$9.99 to get into the Helix exome ecosystem

Will try to keep self-interested product placement to a minimum normally, but I thought I’d pass on that Helix has a $100 off sale for the next 72 hours. That means that the company I work for has a Neanderthal app on sale for $9.99. The regular price is $29.99, and added $80.00 for exome+ sequencing if you aren’t in the Helix database (which most people are not).

The upshot here is that the $9.99 will get you an exome+ sequence, which at some point in early 2018 you can download for $600. But if you don’t want to download it it’s a great way to get into the ecosystem on-the-cheap.

I assume most of my readers know what the exome is, but it’s basically the portion of your genome which is directly translated into functional proteins. That’s about ~1% of the genome, or ~30,000,000 bases. This is a major expansion on the SNP-chip platforms which are DTC which are in the 500,000 to 1,000,000 SNP range.

Anyway, not sure this will be appealing to readers who need a full download of data. But if you are the type who is more interested in getting applications related to your genome, this is a pretty good deal at a sub-$10 price point.

Note: To my knowledge only ships to USA currently.