Greek adult sex
When it came time for a boy to embrace the age group of the adult and to "become a man," he would leave the tribe in the company of an older man for a period of time that constituted a rite of passage.This older man would educate the youth in the ways of Greek life and the responsibilities of adulthood.
Penetrative sex, however, was seen as demeaning for the passive partner, and outside the socially accepted norm.
Whether this was also happening between older women and teenage girls is more controversial because the lives of women are not as well documented.
There was certainly a lot of tolerance for homosexuality in ancient Greece and ancient Rome.
Sparta even encouraged homosexual relationships among its soldiers to increase the chances that one would be willing to die for the other (at least this is the most widely used explanation, which i never found very convincing: what about the abandoned lovers or the jealous lover?
usually love comes with a lot of drama and turmoil).