As is the case for heterosexual people, there is no definitive age that a person discovers their sexual orientation.

While the majority of gay, lesbian, bisexual and pansexual people say they discovered their attraction for people of the same sex at puberty, some people say they felt a difference in infancy. Others say they questioned their sexual orientation much later in life and sometimes even after having been married.

Sources:

Meglioli, Véronique, Bien vivre son homosexualité au féminin, Ed. Jean-Pierre Deville, 2006