Probably not so rare -- every reference I've read says that in American culture, about 10% of us don't have the fathers that we're supposed to. Applying that to the approx. 1-in-200 pregnancies that are twins suggests that 1-in-500 pregnancies has this condition (2 chances at being misconceived per twin pregnancy), or about 0.4% of the population is from such pregnancies, about 1.2 million people in the US.
no subject
Date: 2009-05-20 02:45 am (UTC)