UPDATE.... To my original post on this subject.
Well F' That. I never thought I would be that clueless as a dad.
Looks like I'm a bit behind the times.
We were riding in the car talking about his sex-ed class. Apparently his instructor handed out crudely drawn pictures of the male and female genitalia he had created himself.
So, sensing an opportunity I asked if he wanted to see "real" versions? He replied: "Dad, I have google images." Ahh.
So pressing on I asked if he had any questions that had not been answered by the class. His response: "Yeah, can hermaphrodites get themselves pregnant"?
(I still need to look that one up...)
Oh, and he now has a steady girlfriend.
Case closed.