This is an article published on CNN.
(FindLaw) -- Jerry Lee Lewis is notorious for having married his cousin. So are Charles Darwin and Albert Einstein. All three suffered for having violated a widely held social norm against "incestuous" unions. Yet there may be less reason for this norm, and for the laws enforcing it, than was once believed.
A panoply of state laws say cousin marriages are taboo. But a new report in the Journal of Genetic Counseling, described in the New York Times last week, might send state lawmakers back to work revising their incest laws.
The report concludes that cousins can have children together without running much greater risk than a "normal" couple of their children having genetic abnormalities. Accordingly, the report potentially undermines the primary justification for laws that prevent first cousins from marrying or engaging in sexual relations with one another.
I've also read that chances of having a birth defect between married relatives is 5% and the same chances between a nonrelative couple is 4%. I dont really see that much of a deviation.