According to Simon LeVay, a neuroscientist and writer based in West Hollywood, California, “Bisexual men might have their ‘hyper-heterosexual’ female relatives to thank for their orientation.” He attributes this to an X-linked gene that increases attraction to male sexuality. He claims that even though this genetic link may not be the determining factor in gay and bisexual sexual orientation, it’s certainly seems to influence it.
LeVay refers to a study by Andrea Camperio Ciani and colleagues at the University of Padua, Italy.  They asked 239 men to fill out questionnaires about their families and their past sexual experiences. On the basis of their answers, the men were classified as heterosexual, bisexual or homosexual. The results showed that the maternal aunts, grandmothers and mothers of both bisexual men and homosexuals had more children than those of heterosexual men. They suggest that the genes on the X chromosome may be responsible for influencing a woman’s attitude to men rather than actually increasing her fertility, making her likely to have more children. According to Camperio Ciani and colleagues, the same genetic factor appears to be passed down to both bisexual and homosexual men. .
These findings support some of the studies that we have looked at in previous blogs. A study by Blanchard and associates found that gay men tend to have more older brothers; the likelihood of being gay increased by a third to one half with each male fetus. They suggest that these outcomes may be linked to pheromones. The theory is that mothers develop a higher level of female pheromones to counteract the male pheromones of the fetus with each successive male pregnancy. This may reduce the male pheromones and create a higher percentage of female pheromones thus resulting in female psychological and perhaps even internal physiological characteristics. One last study before the conclusions, a study by Derr way back in 1976 indicated that homosexual men have significantly higher levels of testosterone.
Granted these studies seem to have a whole lot of theory based on a small amount of science; however, the conclusions and possible implications are interesting to say the least. These studies suggest several things. First, the genetic X component may be connected to a heightened awareness and attraction in both men and women to testosterone based pheromones from men. Secondly, males from larger families may be influenced by powerful female pheromones interacting with the male pheromones of the male fetus during pregnancy. Either way, the evidence is mounting for a biological based attraction toward males in gay and bisexual men.
Here are some additional thoughts. Perhaps (just guessing, for after all that is the prerogative of a blogger) the degree of the power of the maternal X may also determine whether we are completely gay or sort of half gay/half heterosexual as in bisexual. A second possibility may be the strength of the forgotten Y component from sexually aggressive fathers. Could it be that the degree of male sexual aggression and increased testosterone in bisexual men simply leads to a powerful drive that neutralizes the aversion aspects of the oxytocin bond? As bisexuals we have a powerful testosterone based drive; we are definitely attracted to men and definitely attracted to women. Furthermore, could it be that we may have a hyper heterosexual/homosexual combined genetic XY factor that increases our drives directing them to male and/or female pheromones?
Perhaps the title should be “hyper-sensitivity”, or “hyper-sexuality”? Perhaps the title should be “hyper-bisexuality”? Could this explain why we are so driven for gay sex even though we have healthy sexual relations with our female partners?
 Bisexuality passed on by ‘hyper-heterosexuals. https://www.newscientist.com/article/dn14543-bisexuality-passed-on-by-hyper-heterosexuals/
 Journal reference: The Journal of Sexual Medicine (DOI:10.1111/j.1743-6109.2008.00944.x)
 Money, 1987. Meyer-Bahlburg, 1995. Blanchard, 2001.
 Peter Doerr, MD; Karl M. Pirke, MD; Gotz Kockott, MD; Franz Dittmar. Further Studies on Sex Hormones in Male Homosexuals. Arch Gen Psychiatry. 1976;33(5):611-614. doi:10.1001/archpsyc.1976.01770050063010.