Yes, the human body does take to heterosexual activity. What of it? Straight womens’ bodies respond to rape with pregnancy as well. But this by no means implies that women are meant for rape.
What I have been trying to explain to you is that a body having a built-in response to an event by no means implies that that event “should” happen. And the lack of a response does not mean that it should not happen.
I will try to say this as clearly as possible. We homosexuals do not believe that we have a different gender from straight people. Lesbeans are still women and gays are still men. A gay’s sperm will still fertilize eggs, and a lesbean can still become pregnant. We can still perform coitus, and this may produce children. Gay or lesbean sex does not produce children. **But this does not make us heterosexual. What evolution designed our bodies for is not what we desire. ** For whatever reason, we are attracted to our own gender. There is not a conflict with our bodies in this. Our bodies define our sex, not our attractions. And those of us who are not part of the religions forbidding gay marriage, see no reason that the love we feel towards each other is any different from the love straight people feel towards each other.