I want to describe how I think of sexual identity and orientation. My thinking is simple and concisely expressed with a thought experiment.
The Nature article No ‘gay gene’: Massive study homes in on genetic basis of human sexuality describes the results of nearly half a million genomes revealed five DNA markers, none of which contributes more than 1% of predictability to orientation. Orientation is multifaceted and complex and very likely for identity, too. The multigene characteristic informs the thought experiment.
Imagine a couple, male and female, identifying cis and heterosexual. In particular, they carry only genes for their respective sex to identify as cis and heterosexual and none for trans and homosexual.
When each individual of the couple forms gametes (egg and sperm), meiosis occurs. Given our above constraint, the female will only have eggs with X chromosomes and female-identifying and male attraction genes. The male will have sperm with male identifying and female attraction genes. Roughly half will have the X chromosome; the remainder will have Y.
When they have children, they can have XX and XY children with an even distribution of male-identifying and female-identifying genes. Similarly, there will be an even distribution of female-attracting and male-attracting genes. The genes expressed will determine how they identify and who they are attracted to. Gene expression could be any combination, though likely biased based on their X/Y configuration (but not guaranteed).
This thought experiment is a simple characterization, but there isn’t any loss of generality considering other layers of complexity, whether that be the genes coding for brain configuration (where expression would still matter) or how synaptic pruning operates.
What do you believe if you don’t believe in genetics/heritability for these characteristics?
- Is it part of brain function? If so, what determines brain function?
- Where does it come from if it isn’t part of brain function?
- Do you think it is a choice if it isn’t biologically determined? Can you choose your own identity or orientation differently?
From a moral compass point of view, a person’s sex, identity, and orientation are only relevant to … sex. If your interaction with a person has nothing to do with sex (friendship, working together, living on the same street, voting, etc.), then it is irrelevant. If a person’s sexuality is relevant to you outside of sex, that is saying a whole lot more about you than it does about them.