The world of synapses
I'll now go into the matter of neurons (nerve cells) and ask what causes synapses to be connected in this way and not otherwise. This is where NGF (Nerve Growth Factor) comes into play. Where it is present, synapses are stabilized; where it is not, apoptosis, programmed cell death, occurs and synapses disappear. BDNF (brain-derived neurotrophic factor) works in the same way, but is found in increased quantities in the brain. I increasingly suspect that NGF expression (the regulated production of the protein NGF in certain cells) is correspondingly structered male or female. And if the NGF expression is actually structured in a sex-specific manner, the corresponding protein will also be distributed differently in a sex-specific manner in the different brain cells (hypothalamus, cortical areas, etc.) and this will change the number of synapse connections in the respective brain areas.
There are many factors involved and if even one factor causes problems, then there is mess, and a full-blown NIBD (neurointersexual body discrepancy) can arise in fetal brain development.
The beautiful and exciting thing is that original Transsexuality (NIBD) / Neurointersexuality can be understood wonderfully and very excitingly in medical, anatomical and biochemical terms. Transgenderism doesn't do that, because it's just a social construct and lifestyle (that's what those affected by transgender say themselves by claiming that "gender can be taught and chosen" - see SBGG - german site).