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Budget_Bathroom_1056 t1_j6jwpgi wrote

Is this a common case in humans aswell?

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405134 t1_j6ki9p9 wrote

Human twins in the womb don’t share blood supply between themselves, the blood comes from the mother , and her blood enters each twin through the umbilical cord separately

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sionnach t1_j6mnp3g wrote

If only that were always true. Twin to Twin Transfusion Syndrome and Twin Anamea Polychthaemia Sequence are pretty horrible things that happen not infrequently in monochorionic (identical) twins.

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405134 t1_j6oufl5 wrote

Wow , that’s gotta be pretty rare though right? And I’m sure situations where twins are conjoined in the womb also potentially could share blood; like conjoined twins

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Yurekuu t1_j6k1jdr wrote

Apparently it does affect the twin somewhat but nowhere near the amount it affects most other mammals. It might be because we take so long to develop and that sex differences aren't so huge at a younger age for humans? That's just a guess from me though.

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Cannie_Flippington t1_j6klcmx wrote

Cows and humans gestate for the same length of time, oddly enough. But they do mature a lot faster...

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audreyba123 t1_j6lm864 wrote

I just read the article you linked, but it says there’s no difference. “SUMMARY Women with a male co-twin had the same chances of being pregnant and having children compared to same-sex twin pairs.”

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anarchyreigns t1_j6l4mrl wrote

The key here is that we need to understand that humans have hormonal influences on their offspring during pregnancy, these influences can result in gender disparities that may make a child feel as though they are misgendered. I wish that people could understand that a person born of one “sex” may never be able to adapt to being that person.

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kweenllama t1_j6m65o2 wrote

Do you have a source for “pregnancy hormones cause gender disparity”? I don’t know if that’s true and I’d love to read about it

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fermango t1_j6l2mz9 wrote

Looked it up. Apparently in 0.1% of male/female twins they can be identical. But this means that the female ends up "losing" a chromosome and rather than becoming XX when the egg splits she is XO. They call this Turner Syndrome and it can lead to a range of medical issues including infertility, just like the cows mentioned above.

In 99.9% of cases involving male/female twins they are non-identical and do not share a placenta so the female is no more likely to be infertile than in singular female babies.

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Redpandaling t1_j6k947w wrote

Probably not. At best, you get hormones passed from the baby through the mom and then to the other baby, but that blood travels a very significant distance between the two babies, which should substantially dilute the hormones.

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zachw055 t1_j6kdr6e wrote

What is considered a significant distance?

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Redpandaling t1_j6khfvj wrote

Uterus => heart => lungs => heart => uterus

And of course it's mixing with blood from the rest of the body the whole way

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sionnach t1_j6mns2r wrote

The shared blood bit, yes it can happen. But only in monochorionic (identical) twins, so you don’t get the “wrong” hormonal exchange I suppose.

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