It should come as no shock to those who read on the issue of same-sex attraction to see studies trying to understand a biological basis for same-sex attraction. It has been, for sometime now, thought that somehow in fetal development, a fetus could be pre-disposed toward same-sex attraction. One theory has tried to explain this pre-disposition via the lines of hormonal washing of the fetus in the uterus through the hormones coming from the mother. This hormonal washing leads to a certain exposure of too much estrogen or too little testosterone upon the fetus in which the brain development is geared differently than what should be. Underlying such theories is the understanding that the male and female brains are different. So, for a man with same-sex attraction, he may have a more "feminine" brain, and for a woman with same-sex attraction, she may have a more "masculine" brain. This biological pre-disposition is just that, something that creates the possibility for a man or woman to have same-sex tendencies.
Bogaert, in his study, suggests there is some sort of prenatal factor that is a "maternal immune response to succeeding male fetuses" similar to "the maternal immune response that can occur when a mother has Rh-negative blood but her fetus has Rh-positive blood. Without treatment, the mother can develop antibodies that may attack the fetus during future pregnancies." But he did not speculate about the exact nature of this maternal immune response. And his research applies only to men, not to women.
Having biological (as opposed to step- or adopted) older brothers does not necessarily mean a younger brother would have a same-sex attraction. "This needs to be looked at in context of the overall rate of same-sex attraction in men, which he suggested is about 3 percent. With several older brothers the rate may increase from 3 percent to 5 percent, he said, but that still means 95 percent of men with several older brothers are heterosexual." Did anybody notice the first shocking statement in this paragraph? The study author, Bogaert, believes that the rate of same-sex attraction in men is at about 3% - not the usual 10% reported in the media and propaganda for "gay" rights and issues. The second statement concerns the study in particular; that 95% to 97% of men with several older brothers are heterosexual.
One thing notably disturbing about the study is Bogaert's attempt to dismiss environmental influences on same-sex attraction. He dismisses environmental influences upon the basis that "men raised with several older step- or adopted brothers do not have an increased chance of being gay." To get at this assertion, Bogaert studied "944 heterosexual and homosexual men with either 'biological' brothers, in this case those who are the same mother, or 'non-biological' brothers, that is adopted, step or half siblings." "He found that the link between the number of older brothers and homosexuality only existed when the siblings shared the same mother." This part of the study assumes, wrong in my opinion, several important distinctions: That the upbringing for biological siblings would be the same and that these siblings are identical in personality and habit. The study seems to suggest that these men would not have unique characteristics and personalities. No child is the same and I don't see how one could rule out environmental factors solely on the basis of biological or non-biological siblings.
While this study explores same-sex attraction in men, where does this leave women and same-sex attraction? Would they have a separate biological basis for a same-sex attraction disposition? This theory leaves much to be desired, first because of its attempt at dismissing without hard evidence environmental influences, and two because it is ultimately a theory and not much of one with conclusive evidence. That is part of the difficulty with the study being done by a psychologist and its limitations in understanding the biological and chemical interactions.
If I come across the study and find something interesting or helpful in explaining things better, I will provide an updated post about my discoveries.
Update: In response to the comment from Diane regarding my thoughts on the subject as well as her questions, I have added below a section regarding the intrauterine influences on the brain development of fetuses.
The quotes you will see below are from Dr. Jeffrey Satinover's article "The Biological Truth about Homosexuality" which appears in Same-Sex Attraction: A Parent's Guide edited by John F. Harvey, OSFS and Gerard V. Bradley.
First, in his article, Dr. Satinover alludes to the possibility that there is some genetic variable in which a person may be more likely to have same-sex attraction. "Whatever genetic contribution to homosexuality exists, it probably contributes not to homosexuality per se but rather to some other trait that makes the homosexual option more readily available than to those who lack this genetic trait." No study has shown with definitive evidence that there is a genetic cause of same-sex attraction.
Second, Dr. Satinover discusses intrauterine influences upon brain development of fetuses.
The hormonal enviornment in which a baby develops is a balance of androgenic (male) and estrogenic (female) hormones. A genetically male baby signals the mother to generate a more heavily androgenic environment than does a female baby. The particular hormonal balance then determines whether the baby will develop typically male or typically female genitalia, bodily characteristics, and brain structures. Because the maternal hormonal response varies, the masculinizing or feminizing influences are different for each developing baby.And while our reproductive organs divide us as male or female, in regards to traits and characteristics, men and women are a mix of male and female traits. There are cases of men who have feminine physical traits and women who have masculine physical traits. All of this is within the normal range of variance for men and women. This difference of the noticeable physical traits carries over to the unseen brain and its development. Here there is overlap as well. There are men who have behavioral characteristics typical of women and vice versa for women.
From time to time the chemical signals get crossed. The maternal hormonal milieu of, for example, a genetically male baby will then be very far to the feminine end of the spectrum. In these unfortunate cases, her genitalia, body type, brain, and behavior will develop physically as a normal-appearing female. She remains, however, genetically male and therefore infertile.... In rare cases, the milieu is ambiguous. Regardless of the baby's genetic structure, the baby will emerge a hermaphrodite - one with variable proportions of male and female features.... Clearly, then, an important determinant of at least certain behavioral predispositions is the hormonal environment. Thus, some proportion of what appears to be genetic in homosexual behavior may actually be a nongenetic intrauterine effect on the parts of the brain that influence sexual behavior. (emphasis added)Much of this influence of hormones remains unexplained, probably because of the difficult nature of understanding the brain and its development. Dr. Satinover concludes his article discussing what he sees as the larger factor in the development of same-sex attraction, and that is environmental influences.
My opinion follows closely with what Fr. John Harvey, founder of Courage and co-editor of this book from which I am quoting, argues. There is not ONE single cause of same-sex attraction. It is more likely to be a complex series of causes stemming from biological and psychological development of the individual. I hope my update has provided more clarity regarding this issue. Feel free to submit questions or comments and I'll try to respond as best as I can.