Yes, x-linked traits with high heritability show up in particularly distinctive patterns in family pedigrees... and while in some mental health disorders, this pattern HAS emerged (notably, in schizo-affective disorder and in some work in personality disorders, though N's tend to be small); it's not ever been shown convincingly in an empirical population study of human intelligence that I'm aware of.

Even a putative x-linkage in some known and fairly well-defined psychosis-producing and highly heritable mental illnesses has been VERY hard to pin down.

Ask families thus affected and they definitely all know it is true... but there are a lot of other genes involved in the population-wide phenomenon, apparently, because only SOME of the families have the x-linked variety.

Personally, I suspect that this is because the empirical endpoint (a complex behavioral construct) is simply a common endpoint for a wide variety of independent underlying causative mechanisms.

Asthma has also been discovered to be like this; it describes symptoms, if you will, not a disorder with a universal mechanism.

I don't know of too many neurological phenomena that this is untrue of, in fact. MOST complex behaviors have several independent underlying causes. No reason to think that inherited intelligence would be any different.


Schrödinger's cat walks into a bar. And doesn't.