These include lifelong monogamy, serial monogamy, polyamory, polyfidelity, promiscuity, group sex, and celibacy.
For those with more than one sexual partner, these may, or may not, all be of the same gender.
For example, sexual attraction and/or behavior may not necessarily be consistent with identity.
Some individuals may identify themselves as homosexual or bisexual without having had any sexual experience.
Others have had homosexual experiences but do not consider themselves to be gay, lesbian, or bisexual.
Although Kinsey's methodology has been criticized, the scale is still widely used in describing the continuum of human sexuality.
Of youths who had identified only as bisexual at earlier assessments, 60-70% continued to identify as bisexual, while approximately 30-40% assumed a gay/lesbian identity over time.
Authors suggested that "although there were youths who consistently self-identified as bisexual throughout the study, for other youths, a bisexual identity served as a transitional identity to a subsequent gay/lesbian identity." Bisexuals commonly start to identify as bisexuals in their early to mid twenties.  Bisexual women more often have their first heterosexual experience before their first homosexual experience, whereas bisexual men will have their first homosexual experience first. A 2002 survey in the United States by National Center for Health Statistics found that 1.8 percent of men ages 18–44 considered themselves bisexual, 2.3 percent homosexual, and 3.9 percent as "something else".
Equally, otherwise heterosexual people who engage in occasional homosexual behavior could be considered bisexual, but may not identify as such.
For people who believe that sexuality is a distinctly defined aspect of the character, this ambiguity is problematic.