If the sperm cell contains a Y chromosome, then the resulting zygote will be (XY) or male. Genes that are found on the sex chromosomes are called sex-linked genes. These genes can be on the X chromosome or on the Y chromosome. If a gene is located on the Y chromosome, it is a Y-linked gene. These genes are only inherited by males because, in most instances, males have a genotype of (XY). Females do not have the Y sex chromosome. Genes that are found on the X chromosome are called X-linked genes. These genes can be inherited by both males and females. Since genes for a trait may have two forms or alleles, one allele is usually dominant and the other is recessive.