There are more genes related to intelligence on the X chromosome than on just the X and Y chromosomes. There are still 22 other pairs of chromosomes, which in offspring, are a mishmash of the father and mother's chromosomes. Genes on these chromosomes have been experimentally linked with intelligence (eg, http://genepi.qimr.edu.au/contents/p/staff/CV453.pdf)
Plus, there are sex differences in intelligence; there are more male dullards and geniuses. Men score higher on visuospatial ability, and women on verbal ability. Given that these are distinctly sex related, their genesis lies in differences between the X and Y chromosomes.
Here is another link: http://discovermagazine.com/2005/oct/sex
There are more genes related to intelligence on the X chromosome than on just the X and Y chromosomes. There are still 22 other pairs of chromosomes, which in offspring, are a mishmash of the father and mother's chromosomes. Genes on these chromosomes have been experimentally linked with intelligence (eg, http://genepi.qimr.edu.au/contents/p/staff/CV453.pdf)
Plus, there are sex differences in intelligence; there are more male dullards and geniuses. Men score higher on visuospatial ability, and women on verbal ability. Given that these are distinctly sex related, their genesis lies in differences between the X and Y chromosomes.