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viridiformica t1_jac8sa7 wrote

Reply to comment by lazercheesecake in Why does temperature determine the sex of certain egg laying animals like crocodiles? by insink2300

>in humans, all babies start off development as females.

I've seen this said a few times, and I'm always curious why the common early development pathway is considered female rather than ungendered?

It doesn't seem like enough to say that it requires activation of masculinising hormones to start being male, since presumably there are any number of hormonal triggers required on either path to spur development

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AMartin223 t1_jaco2pt wrote

I think the main reason for that mindset is that we have these various documented syndromes like described above where failures to emit certain hormones prevent the transition to male anatomy, so it feels more like the female path is the default rather than a different fork in the road. It seems though that describing the early stages either way can be a correct model.

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silent_cat t1_jady8y2 wrote

Well, there are all sorts of genetic abnormalities that cause genetic males to appear female. But none that cause genetic females to appear as male.

Sure, there are any number of hormonal triggers, but if you miss all of them you appear female. Note, it's the appearance that relevant, because with these various syndromes they still tend to have testes rather than ovaries. It appears that the signal to produce a penis however requires an actual on signal.

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foolishle t1_jae88jc wrote

Well actually there have been cases where the SRY gene (the one that triggers masculine development) has been translocated onto the X chromosome which means that a XX person can develop male sex characteristics.

As usual with sex-development it doesn’t seem to matter how much we know, it turns out to be even more complicated than that!

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