Hello @isa93 :)

Thank you for commenting. I see you brought me a lot of questions :D So, I made a cup of tea, turned my music on and here I am 😊 Let's see if I can reply to you in a satisfactory way!

You talk about the existence of a sexual bias, but what about discrimination toward individuals that exhibit homosexual behaviour?

In the studies cited in this post there were no observations of members presenting homosexual behaviour; therefore, not notes were taken about how others reacted to it. But, without any specific study to back me up on this, I would dare to say that this could be manifested in the form of violence or even exclusion against the member who is not fulfilling their group identity part.

Now, biology and psychology are somewhat internal factors, but society exerts an influence from the outside, doesn’t it?

Absolutely :)

At which point can we know whether the behaviour is biological/psychological and when social?

This is the big question! For example, a similar study - MRI exam - was conducted in adult transgenders, and indeed the brain of an adult male who transitioned to become a woman, was more similar (in functionality) to that of a heterosexual woman than that of a man. But, then now ... how to find out whether they were born like that, of if that the brain's network adapted to the social environment in which they developed; in turn giving rise to female's psychological aspects? The fact that we are such complex creatures living in such complex societies makes just really impossible to disentangle the three aspects - social, biological and psychological (and this is the answer to your question!). This is why, like I said in the article, studying non-human animals becomes handy!

Also, if one makes a ‘mistake’ by approaching a child’s GID behaviour a certain way (either reinforcing or trying to change the behavior) does this count as a social influence?

However the approach - reinforcing or preventing - will be an environmental influence. The tricky part here is drawing the line between the child's needs and what is imposed on them. I suppose, this is down to how well the parents know their child and how unbiased they can be in their judgement.

And if it does, is it reversible? Or can such an influence change the individual’s gender identity permanently?

Most psychological states are reversible indeed; let's say another child with a similar case of that to Camille's goes through the same I am a girl phase, but the parents just let him be. Do you want a doll? Here is a doll! But without getting the whole 'you are going to be a girl' mindset around the child. In this case puberty will tell, and it might take the child either way. However, in the case of Camille, I find very difficult that she will feel like a boy in her puberty years, her entire environment is wiring her brain networks to work as that of a girl from a really early age. She is growing up to be a girl. But this won't really matter if Camille grows up to enjoy a life of high-levels of subjective well-being and emotional stability :)

I hope this has helped to clarify some of your doubts, at least a little!
All the best to you & thank you for thinking thing through so carefully. It really makes the work I put into my posts worthwhile!