Some genes on sex chromosomes play a role in sex determination, but these chromosomes also contain genes for other traits. The human X -chromosome is much larger than the Y . Most X -linked genes have no homologous loci on the Y chromosome. Examples of sex-linked traits in humans are color blindness, Duchenne muscular dystrophy and hemophilia. Fathers pass X -linked alleles to only and all of their daughters.
Males receive their X chromosome only from their mothers.
Fathers cannot, therefore, pass sex-linked traits to their sons. B. Mothers can pass sex-linked alleles to both sons and daughters. Females receive two X chromosomes, one from each parent.