In a male with an X-linked recessive disorder, he would have one allele for the disorder on his X chromosome. Since males have only one X chromosome, inheriting a single X-linked recessive allele from their mother would result in the manifestation of the disorder. If a female had the same X-linked recessive allele on one of her X chromosomes, she would not have the disorder because she has a second X chromosome that can carry a normal allele to compensate.
