Birth defects after incestuous mating: calculating the probability of causality and reflecting on the desirability of genetic testing.

In this short communication we (1) show that, despite the rarity of autosomal recessive inheritance, primary congenital hydrocephalus in a girl stemming from father-daughter incest is most likely due to the incestuous union of her parents, and (2) reflect on the question, among others, whether actual genetic work-up to support victim indemnification is ever in the interest of the child.