The biological reality of intersexuality is easier to demonstrate than the likely biological reality of homosexuality. It's impossible to ignore biology when looking at someone with one ball and one ovary, for example - not very realistic suggesting to them that if they just accept Christ they can change.
Homosexuals, on the other hand, bear no outward or chromosomal signs that they are different from heterosexuals. Studies have indicated that homosexuality is likely based in biology:
Studies that I am aware of:
1. Brain scans indicate differences between homosexual and heterosexual men, but those who believe the behaviour is chosen will argue that the changes may occur as a result of homosexual behaviour.
2. More interesting to me, a study which suggests that the more male children a woman has, the more likely it is that one of the younger males will be homosexual. I would like to see this study expanded upon (and sorry, I can't find it at the moment, read it in a newspaper, I think, some time ago). {off topic, sorta, pure, unscientific speculation: The implications, if the study's numbers are confirmed, might even suggest an evolutionary benefit of homosexuality. We have been a farming species for a very long time. There was surely a familial benefit to having sons in large extended farm families who are unlikely to marry or leave home.}
So I don't see how people opposed to homosexuality can even address this topic, but one hopes some of them might be curious enough to read some of the information, and just maybe consider that if biologically intersexed people exist, then biologically homosexual people also exist.
(Man was this post convoluted: sorry, people.)