Gay Genes?

Another day another blog.

I think I failed chemistry last night, so as recompense I feel I ought to incorporate some into this blog.

Today I am blogging (yet again) about the nature/nurture debate surrounding sexuality, with a little bit of scientific research to broaden your understanding (and mine).

For many of us, there is a decisive point at which we can first identify genuine sexual attraction to a member of the same sex. For others, it was something they always knew and accepted, or a gradual development over time.

Looking back, the first time I can really put my finger on it, was one of my best friends in junior high school. While the foundations had long been present, with inklings of same-sex attraction since Louisa C in grade 5 (I've always a been sucker for blondes) it was Miss M.D who forced me out of cosy denial. (I've neglected to mention her name on the preface that she is no longer that way inclined!). I wrote endless diary entries about her, torn as to whom to tell, and how to proceed, surprised and confused about how she made feel. But we're not here to talk about me, I just thought I'd share my own experience about a sexual attraction which I feel I had little control over.

Bring on the science!

A longitudinal study in Toronto, Canada (amongst others) has found that if you are male, the number of older brothers you have appears to affect the likelihood of being gay. The "fraternal birth order effect" suggests that each older brother increases your chances of being homosexual by approximately 30%. This is not thought to be environmental (from examining adoptee children) but rather genetic, and related to the mother's immune system, and the H-Y fetal antigen (present only in males), which can trigger an immune response in mothers. It is thought that mothers’ antibodies may develop a resistance to the H-Y antigen over time with exposure, meaning subsequent male fetuses are exposed to different immuno-environments. Interestingly in support of this, there is no similar correlation in same-sex attracted females.

While on the topic of females, earlier this year a gene was discovered that affects the sexual preferences of female laboratory knockout mice. Knockout mice have genes systematically removed, and when this particular gene is removed, female mice reject the advances of males and instead try to mate with other females. The mouse gene codes for an enzyme that adds sugar to proteins affecting their estrogen levels. The brains of mice embryos lacking the gene are flooded with estrogen and, as a result, develop more like the brains of male mice (with female anatomy). However, it is impossible at this stage to know whether or not there is a similar gene in humans as this particular gene does not code for the same enzyme in humans, and masculinity in humans is controlled by testosterone not estrogen.

Another study (on which I intend to elaborate in the next blog) relating to children raised in same-sex families, found that they were no more likely to consider homosexual relationships than children raised by heterosexual parents. 76 children aged 17 in the US were interviewed and compared to children raised in heterosexual families of similar household income and educational background.

To finish up, here’s a fun one... Take a look at your hands. Pay particular attention to your index and ring fingers. In women, these two fingers are usually almost equal in length. In men, the ring finger tends to be much longer. The ratio of the lengths of the index finger to the ring finger is called the 2D:4D ratio. Low ratios are considered "masculine" while high ratios "feminine" because development of fingers in the womb reflects testosterone levels. Testosterone levels are typically higher in women who experience same-sex attraction.

So next time, kids, when you're parents ask where they went wrong, tell them you're not giving their parenting style all the credit for your amazing sexuality, because some things are just random, due to a little thing called meiosis and DNA.
This is Z, signing out.