David Deutsch wrote:

In view of the above, it is perfectly possible
for a given behaviour to be 100% caused by “part
of the brain not functioning … due to genes … [that] …
render a person unable to will themselves out”, and
yet also to be 100% due to the way other people have
behaved towards that person, or 100% due to the person's
own choices.

Since we have no explanations either way and seeing as we still have the problem of a parent who is completely unable to read body language, despite being given numerous and repeated explanations and despite the fact that he explicitly declares that it would be right to try to solve these sorts of problems, what would one do?

Would one expect the child to change their preferences about being understood non-verbally, or would one just expect to explain oneself repeatedly again and again for all of the forseeable future, or would one think...well maybe we should seek some other kind of solution. Perhaps the problem lies beyond the current scope of our ability to solve it and so we need new and other and better solutions. Until such time that these come about, we are stuck.

Isn't it more humane to imagine that the father is not intentionally wicked or entrenched in these situations?

I agree wholeheartedly that the problems of the creation and treatment of fake diseases is rampant and awful but at the same time this does not mean that disabilities that relate to the capacity to think do not exist and would not benefit from consensual treatment.