This triplet set was not interviewed face-to-face but questionnaires were received from all three and several telephone conversations were held with the MZ pair. See Comments. All types and combinations of twins are sought. They have two identical twin girls and a boy. A number of sections of the brain have been reported to be sexually dimorphic; that is, they vary between men and women. Vasal and VanderLaan provides evidence that if an adaptively designed avuncular male androphilic phenotype exists and its development is contingent on a particular social environment, then a collectivistic cultural context is insufficient, in and of itself, for the expression of such a phenotype.
Sexual practices that significantly reduce the frequency of heterosexual intercourse also significantly decrease the chances of successful reproduction, and for this reason, they would appear to be maladaptive in an evolutionary context following a simple Darwinian model competition amongst individuals of natural selection—on the assumption that homosexuality would reduce this frequency.
Discordance is judged to occur when twins are separated by more than 3 points on the Kinsey scale for example, a K-4 and a K Inresearchers discovered a biological mechanism of gay people who tend to have older brothers. Retrieved 18 August
There is no indication that social environment after birth has an effect on gender identity or sexual orientation.