As a sexual orientation, homosexuality is "an enduring pattern of emotional, romantic, and/or sexual attractions" to people of the same sex. "Along with bisexuality and heterosexuality, homosexuality is one of the three main categories of sexual orientation within the heterosexual–homosexual continuum. Although no single theory on the cause of sexual orientation has yet gained widespread support, scientists favour biologically based theories. There is considerably more evidence supporting non-social, biological causes of sexual orientation than social ones, especially for males. There is no substantive evidence which suggests parenting or early childhood experiences play a role with regard to sexual orientation.