It's not like (despite the star, the angels, and all) they advertised Jesus's true paternity anyway, so whatever explanation was offered would be interesting.

> we know that
>Joseph didn't get to bang until after she gave birth.

According to catholic and some other doctrines, HE NEVER BANGED. Mary remained a virgin her entire life - the doctrine of perpetual virginity. The idea of Mary's perpetual virginity took root fairly quickly - within the first few centuries after Christ - and has maintained a hold on the Christian imagination ever since.

There's some difficulty over this as the Bible refers to Jesus's brothers but official Catholic doctrine skirts that issue.