Homosexuality will never be on equal footing with straight relationships.
Maybe physically they won't as the two ARE different but my concern has always been why should they be treated differently legally? A short, stocky man and a tall, slender man are physically different but they both get the same legal rights.
For one, straight relationships are healthy
Not all heterosexual relationships are healthy. The divorce statistics clearly demonstrate that.
and normal
So what? Being right handed is normal too, but that doesn't make lefties inferior. Normal=/=superior.
and produce offspring
Not all straight couples produce offspring or are capable of producing offspring. And if you're not calling for the termination of marriages where one or both partners are sterile, too old, or choose not to have kids then you don't really have an argument.
gay relationships are unhealthy [AIDS]
Heterosexuals don't get AIDS? This is news to me. Go tell that to the Africans, I dare you.
abnormal
Again, normal=/=superior.
they can never produce an offspring
Again, unless you're going to claim that old people, sterile people, and people who don't want kids are not allowed to have a relationship then you don't have an argument.
because two people of the same sex are not supposed to have sex
Why not? Because it squicks you out? Tough shit. I don't like the idea of old people having sex but you know what I do? I just don't think about it.
What's so great about having a partner that has the exact same body parts as you?
Even as a straight person I can answer that. Who knows how to please a woman better than a woman? And who knows how to please a man better than a man?