Answer:
To carry both of the genes for an allele, the organism must have the homologous chromosomes. Each homologous chromosome will carry one allele for the gene. In males, there is only one X chromosome and one Y chromosome. In females, there are two X chromosomes. Hence, males will carry only one allele for the genes which are present on the X chromosome. On the other hand, females will have both the alleles as they have two X chromosomes.