No I meant transsexuals who feel they have the body of the wrong sex and are therefore not functioning well in those areas of life because of the distress. In the same way that someone with depression or anxiety (or uncontrolled schizophrenia) might not function well in those domains of life until they are treated.
I think we all understand that this is a psychological condition
People who feel they have the wrong sexed body parts to the extent that the intense dysphoria means they can’t experience any intimacy. Medical/ surgical transition in those cases can lead to them feeling more whole, with the right body that feels more ‘like them’ enabling them to be more comfortable with themselves and other people. Therefore improved psychosocial functioning, relationships etc. Male to female or female to male.
We don't offer surgical procedures for people with psychological conditions. Mainly because, as with transpeople, those surgeries don't, in the medium and ling term, offer any cessation of mental distress, including suicide ideation.
The processes that affect sex differentiation during foetal development affect both the phenotype of the body and neurological development in the brain and there are crucial periods that are more sensitive to one or the other. I don’t just think that, it’s basic human embryology. I think within that there’s a plausible explanation for contributory biological factors to the development of transsexuality or cross sex identity. (And yes sexual orientation. But let’s not pretend the two are not in some ways connected).
Basic human embriology? OK 
There is some interesting nascent work on that, but it is so complicated, has so many confounding variables, that the very clever people who run the research programmes conclude that they can't even state any true correlations, let alone causality. A light touch conclusion is that, as with many other studies, there might be a predisposition. That it is not inevitable or global, needs to meet the correct societal/nurture factors, which are also not inevitable or global.
Put simply: there is a lot more work to be done, this could be something, it could be nothing. Work in progress.