Most researchers view homosexuality on a sliding scale.
The Kinsey Heterosexual-Homosexual Rating Scale, The Klein Sexual Orientation Grid (or KSOG), & the Epstein Sexual Orientation Inventory (ESOI) all recognize that sexual orientation is more than just Straight, Bisexual, or Gay.
The Kinsey scale is from 0 to 6:
0 = Exclusively heterosexual with no homosexual
1 = Predominantly heterosexual, only incidentally homosexual
2 = Predominantly heterosexual, but more than incidentally homosexual
3 = Equally heterosexual and homosexual
4 = Predominantly homosexual, but more than incidentally heterosexual
5 = Predominantly homosexual, only incidentally heterosexual
6 = Exclusively homosexual
The Klein Sexual Orientation Grid (or KSOG) is from 1 to 7:
1 = Heterosexual only
2 = Heterosexual mostly
3 = Heterosexual somewhat more
4 = Hetero/Gay-Lesbian equally
5 = Gay/Lesbian somewhat more
6 = Gay/Lesbian mostly
7 = Gay/Lesbian only
The Epstein Sexual Orientation Survey (ESOI) has a Sexual Orientation Continuum from 0 (Heterosexual) to 13 (Homosexual) that consists of a Mean Sexual Orientation and a Sexual Orientation Range.