Final answer:
Fragile X syndrome is more common in males because it is an X-linked recessive disorder and males only have one X chromosome, making them more likely to express this condition. Females must have two copies of the recessive allele, and due to X inactivation, carrier females often show fewer symptoms.
Step-by-step explanation:
Fragile X syndrome is more common in males because it is an X-linked recessive disorder. Males have only one X chromosome, so the presence of a single fragile X allele will result in the disorder. On the other hand, females have two X chromosomes, thus needing two copies of the recessive allele to express the disorder, which is much less likely. Furthermore, due to X inactivation in females, where one of the X chromosomes is largely inactivated, female carriers may exhibit fewer or no symptoms.
Discoveries in fruit fly genetics demonstrate that when a female parent is homozygous for a recessive X-linked trait, all male offspring will inherit the trait as they acquire their sole X chromosome from the mother and a Y chromosome from the father, making the display of X-linked disorders more frequent in males than females.