What accounts for the difference of sex-linked disorders between males and females?
These disorders are caused by errant genes. Most of the time everyone has 2 copies of a gene (ie you have two types for haircolor) but one is dominant over the other, causing it to be the only kind observed (you have blue eyes and brown eye genes but brown is dominant – you need 2 to show the recessive trait). Many of the sex linked disorders that are more prevalent in males than females are because the disease gene is located on the X chromosome. Since men only have one copy of X genes (XY = male) and women have 2 (XX), women have a better change of silencing the recessive disease gene then men. This also means that women can be carriers and still pass their diseased X chromosome to a child but not have the disease itself. A common example of such a trait is color-blindness, which mothers can pass to their sons at a 50% rate, but will not pass to their daughters ever if the father isn’t color blind.
