This is a decent overview, but it's worth pointing out that while we do know that "the process is complicated", we mostly don't know which aspects of the process have which consequences for development of gender identity--certainly not in any great detail, anyway, even if we have a few correlations.

In particular, although it's always a bit dubious to read out from biology whether "something is wrong with them", we're not really in a position to say anything a biologically-informed way about the matter.

I think it's better to move away from considering "something wrong with them" as a reason to treat people poorly, or to fail to help them with the "something". People with allergies have "something wrong with them" (they want to fix it), but we don't shun them for it. People with cleft lip have "something wrong with them", but we don't shun them instead of giving them surgery to fix the issue. And these are both completely independent of whether we understand the biological and developmental basis for allergies or cleft lip.