Finding hidden incest

Another unexpected result of gene chips: Identifying hidden incest in the course of routine tests for developmental disabilities:

Houston doctors are reporting that the newest generation of DNA testing, now in wide use, is revealing many previously missed incest cases that raise difficult legal and ethical questions.
Children born to first-degree relatives have a developmental disability about half the time, said Beaudet.
Baylor began using the new test about six months ago. During that time, Beaudet said, the lab has seen evidence of incest fewer than 10 times.

“Half the time” seems high to me, but would explain the high positive rate here.

(via Razib)