Gender and sex in genetics

[Anonymous No.9039247]

So what's the deal with sex and gender in genetics? It seems like there's evidence to say sex and gender are not binary, but then some other sources say they are.

Any geneticists on /sci/ want to give me the rundown?

[Anonymous No.9039632]

The non-binary-ness isn't really in genetics for the most part. There are some weird combinations like XY, XYY, XXX and so on, but for the most part "genetic sex" is defined by the presence or absense of a Y chromosome, which by definition is a binary state - you either have it or you don't. Intersex conditions generally occur either when the "important part" of the Y chromosome is absent (or somehow ends up on an X chromosome in someone who lacks a Y chromosome entirely), or when the body doesn't respond as expected to the "signals" sent out by the sex chromosomes. That's where the real "gender is a spectrum" thing comes in - it's ultimately determined (in typical cases at least) by what sex chromosomes you have, but those cause a lot of individual biological processes to occur which result in males and females ending up physically different, but there's plenty of room for one or more of those processes to "go wrong" and not give the typical results for a given genetic sex. That's how you end up with trans people, for example - the prevailing theory is that most of the body develops normally according to their sex chromosomes, but due to a hormone imbalance prior to birth, the brain ends up developing more like the opposite sex.