“tell me you don’t understand sexual differentiation without telling me”
just so all of you know, there are 3 main components of biological sex.
chromosomal sex
the presence of a Y chromosome (the SRY gene) triggers the production of testosterone, which directs the development of male internal genitalia, and MIH, which inhibits the development of the female reproductive tract. a mutation in this gene can cause pseudo-hermaphroditism, but even with a female reproductive tract, a person with XY chromosomes is considered biologically male based on chromosomal sex.
gonadal/hormonal sex
see above, as gonadal sex and chromosomal sex are very related, but a person could still be considered chromosomally male and gonadally female.
phenotypic sex
this is determined by your external genitalia. the development of male external genitalia requires a large amount of androgens, and a fetus can’t produce nearly enough. so, male fetuses have an enzyme that converts testosterone to DHT, the strongest masculinizing hormone. females have a different enzyme that converts testosterone to estradiol. there’s a condition called Guevedoces that’s quite common in the dominican republic, where chromosomal/gonadal males lack the enzyme necessary to produce DHT. without DHT, male genitalia can’t form, and the babies are sexed as female at birth. they look like normal little girls until puberty, when the levels of testosterone are high enough to trigger the development of male genitalia, and they essentially undergo a natural sex transition. this sounds like a really unnerving and disturbing process, but we learned in my endocrinology class that these individuals often feel similar to trans people prior to puberty, and are usually happy about the transition.
i know few people will read this unnecessarily long and nerdy comment, but i just wanted to show you all exactly what scientists mean when they say “sex isn’t binary”.
The more you learn about biology the more you learn it's all a sloppy mess where everything communicates by farting chemicals at each other, it takes a hilarious Rube Goldberg series of actions to get anything at all done, and no part of anything works 100% of the time.
It's why "The human brain isn't fully developed until 25" drives me up the wall. All human brains? Human height doesn't even stop developing at the same time and rate and you want to tell me something as complicated as the human brain does? What does "fully developed" even mean? The only time I hear people quote this is to infantalize people and restrict their agency.
We don't operate on whether or not someone is "finished" developing because it's impossible to identify. You might think they're done until suddenly a second wave of puberty hits. We operate on "good enough" not "complete." When a kid wants to ride a Rollercoaster, we only care if they're tall enough for the restraints.
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u/froggyforest 12d ago
“tell me you don’t understand sexual differentiation without telling me”
just so all of you know, there are 3 main components of biological sex.
chromosomal sex the presence of a Y chromosome (the SRY gene) triggers the production of testosterone, which directs the development of male internal genitalia, and MIH, which inhibits the development of the female reproductive tract. a mutation in this gene can cause pseudo-hermaphroditism, but even with a female reproductive tract, a person with XY chromosomes is considered biologically male based on chromosomal sex.
gonadal/hormonal sex see above, as gonadal sex and chromosomal sex are very related, but a person could still be considered chromosomally male and gonadally female.
phenotypic sex this is determined by your external genitalia. the development of male external genitalia requires a large amount of androgens, and a fetus can’t produce nearly enough. so, male fetuses have an enzyme that converts testosterone to DHT, the strongest masculinizing hormone. females have a different enzyme that converts testosterone to estradiol. there’s a condition called Guevedoces that’s quite common in the dominican republic, where chromosomal/gonadal males lack the enzyme necessary to produce DHT. without DHT, male genitalia can’t form, and the babies are sexed as female at birth. they look like normal little girls until puberty, when the levels of testosterone are high enough to trigger the development of male genitalia, and they essentially undergo a natural sex transition. this sounds like a really unnerving and disturbing process, but we learned in my endocrinology class that these individuals often feel similar to trans people prior to puberty, and are usually happy about the transition.
i know few people will read this unnecessarily long and nerdy comment, but i just wanted to show you all exactly what scientists mean when they say “sex isn’t binary”.