The evolutionary psychology answer:
If you get a virgin pregnant you can be sure the baby's yours, so you don't waste precious resources feeding some other bloke's offspring. Meanwhile, for women there's a big evolutionary benefit to getting a strong, sexy man to father your children while a nice, responsible man does the work of bringing them up.

Not saying it's the right answer, but it's the standard one and makes sense to me. Read Stephen Pinker for lots of interesting stuff along these lines.
( flatfrog Staring vacantly into space, Wed 21 Oct 2009, 9:27, 1 reply)

Hmmm sounds like bollocks to me.
I still think its the small cock thing
(Bonzodog29 is an unemployed sponge of the worst kind, Wed 21 Oct 2009, 9:33, closed)

I think for most people round here it's because if she's a virgin,
she's more likely to be 11
(TheColonel, Wed 21 Oct 2009, 9:39, closed)

^^^^^
nicely put, I did mirth most merrily
(Bonzodog29 is an unemployed sponge of the worst kind, Wed 21 Oct 2009, 9:41, closed)