Latin had no concept of or even word for heterosexuality or homosexuality. Thus, while you can say Vergil prefers men, or has a distate for women, you can't in Latin call him a homosexual. Likewise, you can't call Claudius, who had an abnormal preference for women, a heterosexual. The Romans divided sexuality between the passive and the active, or the penetrated and the penetrator. Women and boys beneath the age of political responsibility were expected to take a passive role in sex, while men, especially those above the age of 30, were expected to take an active role. This was a social norm, and certainly not a definite rule. Even so, there are examples of men being mocked for their passive sexual role; some of the most insulting epithets were 'cinaedus' and 'pathicus', or 'cock sucker' and...ummm, English words always fail me here...'sufferer', literally, someone who submits to anal sex. Similarly, there are two verbs to describe a blowjob, 'irumare' and 'fellare', the former meaning to put your dick in someone's mouth, the latter to suck dick. Likewise, Cunnilingus was seen as the penetration of the man, and so a passive act. Women who enjoyed sex too much, such as Clodia Metella of Cicero's Pro Caelio and Catullan fame, then took on the male role as well.

This works as well for the initiation of a sexual act. A woman or young boy was expected to be pursued, while the man courted him/her. Tiberius was inherently masculine despite his piscii, young boys he hired to swim naked for him in his pool.

This gets rather more complicated when it comes to prostitution. Prostitutes by their very nature take an active role in sex, if only by the implication of its enjoyment and active procurement. A prostitute thus assumed a male sexual role; she was allowed to wear the toga virilis, and most regulars were enrolled at the end of the Augustan age on a register. One of the great scandals was the self-registration of Julia, Augustus' daughter, on the list to avoid the adultery laws. Nevertheless, their acts were feminine; it was only by the nature of their business and the implied pleasure that they assumed a masculine sexuality.

Sex was a rather developed art. Transgenderism was rampant; certainly it was implicit in the Bona Dea affair, and the later imperial antics of Ellagabalus. The Warren Cup offers us a decent example of voyeurism. Pompeiian Grafitti gives us both bawdy jokes about dick sizes and vivid illustrations of positions, while Martial is an endless source of jokes on vaginal smells, dick jokes, and the typically Roman sense of humour.