> The masculinity and femininity contributed by one full-time parent from each sex.

Despite the many social pressures brought to bear, people do not universally exhibit the gender roles and behaviors expected of them in their particular cultures.

What of, for example, butch women or effeminate men in heterosexual parenting relationships? I know gay and lesbian couples who have a substantially more "balanced" mixture of masculine and feminine characteristics than did my own, heterosexual parents.