Final answer:
Sex-linked traits appear more commonly in males due to their single X chromosome. Females with one recessive gene are carriers and can pass on the trait without expressing it. X-linked disorders like color blindness and hemophilia are examples of such traits.
Step-by-step explanation:
The sex-linked traits are more common in males because they only have one X chromosome, and thus any recessive allele on that chromosome will be expressed. Females, however, have two X chromosomes, so they can be carriers without expressing the trait. A female is a carrier when she has one recessive mutant allele for an X-linked trait and one dominant allele; she does not typically show symptoms because the dominant allele masks the recessive. However, she can pass on the recessive allele to her offspring. If she has a son, he may express the trait since he receives only one X chromosome from her. If she has a daughter, that daughter may become a carrier like the mother. This transmission of traits leads to X-linked disorders, such as red-green color blindness and hemophilia, being more frequent in males.