I hate to bring up a subject loaded with landmines, but alas, I can't
think of who else to ask.

A popular position on abortion is that there should be an exception for
rape and incest.

I certainly understand an exception for rape. The girl or woman didn't
do anything to cause the pregnancy and who wants to give birth to the
child of a rapist. OTOH, who wants to give up for adoption one's own
child, even if the father was a rapist. And is what makes a man a
rapist even slightly genetic? If so, who wants to keep it or even give
it away?

But why is an exception for incest so popular? If the female is a
minor, and the male more than a year or two older, it's statutory rape
and covered by the rape exception. If it's not forcible rape and the
female is over 18, she's thought to know what's she's doing, so why does
she deserve an exception?
Do people want the exception
a) just for the sake of voluntary sex between minors and siblings
who are no more than 1 or 2 years older (in states where that is not
rape)?
b) because of possible birth defects.


I think b is more likely that a, but no one ever mentions either reason.
They just say incest.

So what do you think the reason is?