There's no public debate on how heterosexuals "became that way," but homosexuality seems to require an explanation, with much of the debate now tied to public policy discussions. The present flap over Sen. Kerry's remarks about VP Cheney's daughter prompted this USA Today story which quoted Pres. Bush's "I don't know" reply at the most recent debate, then added a couple of opinions from experts in the field:
In Wednesday's debate, Bush had this response when asked whether homosexuality was a choice: "I don't know. I just don't know."
Research on the question is sparse. Most scientists agree that sexual orientation is most likely the result of an interaction of environmental, cognitive and biological factors, according to the American Psychological Association.
Psychologist J. Michael Bailey of Northwestern University in Illinois, who has done research on sexual orientation, says, "The evidence is not entirely persuasive for either side." Psychologist Gregory Herek of the University of California-Davis says, "There are genetic and social roots for all behavior."
So the medical profession or "science" seems to be saying, "We don't know either," thus agreeing with Pres. Bush's position. I was kind of surprised to see these quotes in the media. See also my prior posts linking to some LDS views on this interesting subject here and here.