Assuming the association between high IQ and various mental/physical disorders is true (evidence for which has been shown in several scientific studies), there

Assuming the association between high IQ and various mental/physical disorders is true (evidence for which has been shown in several scientific studies), there seems to be a simple explanation: the hidden variable is gene networks which are responsible for both effects, which tend to lead to individuals who are on average as phenotypically fit wrt survival/procreation as those with simultaneously lower IQs and lower rates of disorders.