In relation to this article: A high density of X-linked genes for general cognitive ability: a run-away process shaping human evolution?
Questions: 1.) What do you make of it? 2.) What would happen if one or two or more are passed down? 3.) How do we know this is recessive and not incomplete dominant?
Have I thoroughly answered the questions asked? Do I make sense? Is my answer even correct?
Comparatively a large percentage of occurrences of mental disability and infertility are caused by genes carried on the X chromosome, of which males have one and females have two. Whether X or Y chromosomes, offspring are expressed in male children. Female children can carry them to the F2 generation and continue to future generations. However, if the phenotype is expressed in males, the mental disability is paired with fertility issues and therefore unlikely to be passed down to his offspring as they don't carry any. If more than one of the MRX genes are passed down, I believe it would increase the likelihood for a phenotype to show up in male offspring as well as increase the likelihood of passing one or several down to female offspring as well, statistically speaking. I would say that we know this is recessive and not incomplete dominant because the Y doesn't carry any MRX gene in this case so it either is or it isn't, there is no in between.