The Whiteheads believe that we are created with free will and therefore can control all of our actions. They further believe that genes play little or no part in sexual orientation. Rather, I would offer that we have evolved to a high degree of being "proactive" with the environment rather that being mostly led by instinct as were our early ancestors and other primates. This leaves room for inherent differences that result in varying degrees of behavior that is natural.
On several occasions, the authors failed to recognize or report viable alternate inferences from the data. For example, in Chapter Six they discuss the different homosexual and heterosexual practices of several cultures. They conclude that history and culture shows that homosexuality is self taught (p. 114). However, it is possible to infer that forced homosexuality among heterosexuals does not preclude the possibility of genetically fixed homosexual orientation. Further, I believe the extent of homosexual orientation cannot easily be determined in cultures where avowed heterosexuals practice homosexuality.
Similarly, data from four studies of twins show that exclusive homosexuality was four times higher (3.8% vs. 0.9%) than in the general population (p. 156). This they conclude must be due to errors or unusual psychodynamic effects. One could infer that this data supports some degree of genetically "dominated" homosexuality. Also, they dismiss results that don't agree with their thesis (p. 180).
Chapter Twelve is most disturbing. The authors begin by stating that because some homosexuals can change their orientation, it shows that the homosexuality is not inborn. It is possible that the only change is behavior rather than basic orientation. They offer no explanation why many homosexuals who have tried to change, cannot change. Why is this so? One could conclude that perhaps there is true homosexual orientation.
The Whiteheads discussion of homosexual relationships seems to cast homosexuality as being perverted, i. e., mostly unfaithful, compulsive, hyper-sexual and promiscuous (pps. 198-200). The promiscuity data from 1978 may be correct, but the authors do not raise the possibility that the data might have been different if society would have been more tolerant (less homophobic) and, for example, accepted same sex marriages.
In the final analyses, I expect that it does not make much difference if homosexual orientation and practices are determined mostly by genes or by the environment. The individual involved had little to do with the events during their own conditioning. Why can't we just accept that and live and let live? Who would be hurt? Why homophobia? As repugnant as the practice of homosexuality is to me, I have yet to understand how I have been "harmed" by homosexual practices.
I have two homosexual friends. They and their live-in partners are making positive contributions to society. Would they have been better off if they had they been forced to change their sexual orientation? Would we have been better had we been the ones doing forcing the change? That, to me, is the important question.