Causes of Same Sex Attraction … are manifold… including conscious and subconscious Choice… That said, Genetic Determination of Behaviors is not only someone’s guess, it was virtually rejected by many once the Sequence of Human Genome was unfurled - roughly 2000 AD…, In spite of attempts to deny this following, no GENE has been shown which makes someone choose to have sex with someone or something other than their opposite-gender Husband and/or Wife
Sequencing the human genome did not prove that there are no genes that influence someone’s sexual orientation. All this did is tell us what the DNA sequence is for the individuals used to form a reference genome that other humans can be compared against. It is nothing more than a huge sequence about 3 billion units long of one of four possible nucleotides: cytosine ( C), guanine (G), adenine (A) or thymine (T). I had more than 10 million base pairs of my Y chromosome sequenced. One little section of one strand of my Y chromosome sequence reads like this:
CTGTACTGTACTATACTATACTATACTATACTATACTATACTATACTATACCATACTATACTATACTATACCATA
So, what does that tell us? It doesn’t tell us much since we have no idea what that sequence means or what it does if anything. The huge sequences in other chromosomes are similar to this. Some of them are known to contain genes, i.e. coding regions or sequences of nucleotides in DNA or RNA that code for molecules that have a function. Some DNA sequences, on the other hand, are called “junk DNA” because they don’t seem to do anything as far as we know. But we don’t know for sure because we don’t yet know what the function of many sequences is. And although genes might not determine people’s behaviors, many genes certainly
influence their behaviors. And it’s rare for most behaviors or characteristics to be determined by one single gene. In most cases, there are probably multiple genes involved which interact with the environment and figuring out what those multiple genes are and how they interact is very complicated.
Just to give an example involving ADHD, something which I’ve studied a lot about, it has been shown that it is highly heritable. If someone has a parent or sibling or child with ADHD, they are much more likely to have ADHD themselves. But no single ADHD gene has been found. Genome wide scans have found some genes that might be associated with ADHD, but as one expert on the subject has stated, “yet even these associations are small and consistent with the idea that the genetic vulnerability to ADHD is mediated by many genes of small effect.”
It’s unlikely that a single “gay gene” will be found, but, someone’s “genetic vulnerability” to homosexuality might be “mediated by many genes of small effect.”