Why are males more likely than females to have a sex-linked trait that is recessive?

Question

forgot my science book...

Answer 1

no females are more likely to have the recessive sex-linked trait because it is carried on the X and since the boy only has one X they will always show that...however girls have 2 X's so they could show the dominate one.

Answer 2

What you mean is, males are likely to express the trait, but females are more likely to be carriers without expressing it. The best example of this is the haemophilia that was carried by many of the royal families of Europe - the boys had the condition, the females were carriers.

The reason is that boys only have a single X chromosome. So any condition carried on that chromosome will always be expressed. Females have two X chromosomes, so any faulty gene on one of these will be overriden by the healthy copy on the other one. However they have a 50% chance of passing it onto their male descendants.