Conventional wisdom suggests the large X-effect comes about because the X chromosome is "exposed," meaning its complement, the Y chromosome, doesn't have the information needed to mask the effects of changes on the X. We inherit a set of chromosomes from each parent with each chromosome acting as a sort of backup for its complement. "It's a bit like cross-referencing two encyclopedias for errors," said Presgraves. In the case of X and Y, however, it's like trying to cross-reference an encyclopedia with a pamphlet.
Being fairly familiar with genetic-oriented recessive traits, this is just hilarious to me. When you look at images of chromosomes taken under a microscope, the Y is such a runty little bugger. It always amuses me how much of the war and violence in this world are related to that tiny bugger.
