Final answer:
Sex linkage, or X-linked traits, refers to the inheritance of traits located on genes on the sex chromosomes. In humans, females have two X chromosomes while males have one X and one Y chromosome. X-linked traits are more likely to appear in males, as they only need to inherit one recessive mutant X allele to express the trait.
Step-by-step explanation:
Sex linkage, also known as X-linked traits, refers to the inheritance of traits that are located on genes on the sex chromosomes. In humans, females have two X chromosomes (XX) and males have one X chromosome and one Y chromosome (XY). Genes located on the X chromosome but not on the Y chromosome are said to be X-linked. This means that these traits are more likely to appear in males, as they only need to inherit one recessive mutant X allele to express the trait, while females need to inherit recessive X-linked alleles from both parents to express the trait.