While most people want to believe their traits are innate, the fact is Rome wouldn’t have been able to function the way it did if this were true. The existence of Rome and its sex as an institution empirically disproves the hypothesis.

I’m sure there were some men in Rome that were disgusted by the prospect of sex with men and either did it anyway as a duty or found every excuse not to, and I’m sure there were men that salivated at the idea from an early age. But by and large most of the men’s sexuality was malleable. This is certainly also the case today, there are probably some people strongly predisposed to one or the other from birth, but for most people sexuality is largely conditioning.