"I've read that in cultures where virginity at marriage is highly valued like Rio, girls will have anal sex to preserve it."
My brother, who spent years in the middle east, said that because virginity is a requirement at marriage, that the men have sex with other men until marriage, and even after.
They don't consider themselves gay (like men in prison) unless they are on the bottom. A man's sex drive is powerful. If a man in a traditional culture must be financially stable before marriage (and provide a large dowry), he might be 30 before he gets a wife. Do people honestly believe they abstain until then?
So if asked, they would deny homosexuality as being a risk factor, yes?