I didn't say they CAN'T. Of course they can, biologically. And many did in the past, when they found themselves in "show" marriages. But if left to their own devices to be exclusively homosexual, they're not going to breed. And many didn't (think of the homosexuals who spent their lives single as travelling entertainers in the days before electricity and mass media.)

And boy, do you make a lot of assumptions about who you're talking to. They're all wrong, btw.