I have a deep passion for genetics. I am equally interested in historical population studies than in medical predispositions. There is one thing, however, which I really don't care about and that seems nevertheless to be one of the engines driving DNA testing companies : finding distant relatives.
23andMe has released a Relative Finder feature recently. Family Tree DNA has announced today that it would launch a similar service in a month's time. All Y-DNA and mtDNA testing companies already advertised their products as a way of finding long lost relatives, such as 3rd, 4th, 5th or 6th cousins. But why would anybody want to know such distant relatives ?
I could imagine that people want to meet people similar to them. But sharing a bit of DNA does not guarantee any compatibility of tastes, opinions, interests or character. In fact even first cousins rarely share any of these compared to strangers. In many families parents and children or siblings do not even see eye in eye about most things.
Then cousins really do not share that much DNA with us. Theoretically first cousins inherited in average 12.5% of DNA identical to ours. That's just an average. It could be 20%, but it could just as well be 0%. Still theoretically, second cousins share a bit over 3% of our genome, not much than a great-great-great-grand-parent !
A third cousin will hardly ever have more than 1% of common genetic sequence with you, and beyond that (4th, 5th, and so on) you are pretty much as closely related as you are to your neighbours or friends.
If you come from the countryside and your family has lived in the same region for many centuries, like most people in Eurasia, then a haphazard individual from your county or province will generally be distant cousins of yours.
Knowing this I would rather try to find people who share my interests and tastes instead of looking for distant relatives. Why would one rationally pay money to have a small chance of stumbling upon such relatives is beyond my comprehension.
23andMe has released a Relative Finder feature recently. Family Tree DNA has announced today that it would launch a similar service in a month's time. All Y-DNA and mtDNA testing companies already advertised their products as a way of finding long lost relatives, such as 3rd, 4th, 5th or 6th cousins. But why would anybody want to know such distant relatives ?
I could imagine that people want to meet people similar to them. But sharing a bit of DNA does not guarantee any compatibility of tastes, opinions, interests or character. In fact even first cousins rarely share any of these compared to strangers. In many families parents and children or siblings do not even see eye in eye about most things.
Then cousins really do not share that much DNA with us. Theoretically first cousins inherited in average 12.5% of DNA identical to ours. That's just an average. It could be 20%, but it could just as well be 0%. Still theoretically, second cousins share a bit over 3% of our genome, not much than a great-great-great-grand-parent !
A third cousin will hardly ever have more than 1% of common genetic sequence with you, and beyond that (4th, 5th, and so on) you are pretty much as closely related as you are to your neighbours or friends.
If you come from the countryside and your family has lived in the same region for many centuries, like most people in Eurasia, then a haphazard individual from your county or province will generally be distant cousins of yours.
Knowing this I would rather try to find people who share my interests and tastes instead of looking for distant relatives. Why would one rationally pay money to have a small chance of stumbling upon such relatives is beyond my comprehension.