
Immune Cells Play Key Role in Determining Male or Female Traits in the Brain - laurex
https://neurosciencenews.com/sexual-characteristics-immune-cells-9849/
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danieltillett
There has always been some speculation that immunology plays a role in sexual
traits given the fraternal birth order effect (i.e. a son is more likely to be
homosexual the more older brothers he has) [0].

0\.
[https://www.ncbi.nlm.nih.gov/pubmed/28608293](https://www.ncbi.nlm.nih.gov/pubmed/28608293)

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appleflaxen
why would the presence of a fraternal birth order effect mean that it's
immunological?

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dooglius
The paper explains,

According to this maternal immune hypothesis, cells (or cell fragments) from
male fetuses enter the maternal circulation during childbirth or perhaps
earlier in pregnancy. These cells include substances that occur only on the
surfaces of male cells, primarily male brain cells. The mother’s immune system
recognizes these male-specific molecules as foreign and produces antibodies to
them. When the mother later becomes pregnant with another male fetus, her
antibodies cross the placental barrier and enter the fetal brain. Once in the
brain, these antibodies bind to male-specific molecules on the surface of
neurons. This prevents these neurons from‘‘wiring-up’’in the male-typical
pattern, so that the individual will later be attracted to men rather than
women.

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chacham15
Could this play a role in causing Gender dysphoria?

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zaarn
Maybe. Maybe not.

From what I read on the topic, it's much more complicated. People have plenty
of typical-female or typical-male parts of brain slushed around, generally
people tend to have the most of them that correspond to their gender (IIRC you
can guess gender/sex correctly about 80 or 90% of the time by looking at the
brain).

It may contribute along with other factors for the cases where the brain does
express gender dysphoria.

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ashleyn
Gender dysphoria also isn't a clean distinction between "male" and "wanting to
be female". The underlying phenomenon is observed to be rooted in sex-specific
instincts and feelings inverse to what is normally found in people of the same
sex. The interpretation is cultural. Indians believe it means there are two
spirits in a single body, Mexicans have the "mux", and even in the west
there's been tacit admission by some trans people that they feel _different_
but couldn't tell you they were actually _female_...the oft-maligned
"nonbinary".

So really, I don't personally believe a brain can be cleanly male or cleanly
female. Rather, if specific parts are formed differently than usual, then they
respond differently to external stimuli. This can result in a wide range of
sex-atypical behaviour ranging from mere homosexuality to finding one's
genitals revolting. How you interpret that objective phenomenon is really up
to the individual.

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zaarn
I think the brains that are cleanly male-trait or female-trait are very very
rare, most are a mix but there is usually enough difference to be able to make
a very good guess.

Though I also do agree that gender dysphoria can have many different
expressions, once you drop gender you get into a whole new world of stuffs
where people hate various things about themselves (I've met people with self-
described "whole body dysphoria" who are generally okay with their gender and
simply hate the physical existence of their body)

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cperciva
Does this mean that antihistamines could have an effect on brain development?

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neuroma
Yes, but you'd probably need to take them for long periods at high doses
during crucial developmental stages, to provide continuous blockade of the
system. Note also receptor specificity and blood brain barrier penetration of
over-the-counter anti-histamines may lead to less-than-exciting results.

