The Neanderthal theory
This theory aims at giving a credible explanation for why up to 10% in some parts of the world are classified by psychiatry as disordered. Psychiatry themselves have long been on the wrong track, and lack any coherent theory. Some other people in our society like to put all the blame on parents, and this has caused considerable harm to many families.
Recently, some researchers have shown the large amount of genes contributing to these proposed disorders, as well as providing links between virtually all disorders. It's also very clear that there doesn't exist any clear border's between various diagnosis, nor to normality.
The main problem seems to be in the area of non-verbal communications and social behaviors. After a closer study of the topic, it's clear that the non-verbal communication problens are not defects. They are simply different functions, lack of function and sometimes additional functions. The problem is how to explain this in an evolutionary model. Differences in innate, non-verbal communications are very big disadvantages. They can only develop in isolation. Long isolation.
All this lead me to study our history. The only isolated population in recent times, that had been isolated for a long time, was Neanderthals. Closer study of them revealed that anthropology wanted to make sure to exclude them from our gene-pool. However, the reason for this is obscure. The reasoning is only based on phylogenic analysis of mitochondria-DNA. The archeological evidence isn't conclusive, rather it indicates both species cohabitated for a long time in Europe. Evidence is also based on most alleles being more diverse in Africa. However, the more you think about it, the less sense it makes. If two species cohabitate for millennia, it's not very likely hybrids were frequent, and that in turn means mitochondria-DNA of the minority-contributor would be eliminated by genetic drift. Even worse, diversity was reduced by the last ice-age maximum, that caused dramatic movements and most probably a major bottleneck in Europe, but not in Africa.