What are sex-linked traits?

Sex-linked traits refer specifically to characteristics or conditions that stem from genes located on the sex chromosomes, which in humans are the X and Y chromosomes. Because these chromosomes are responsible for determining an individual's sex, the inheritance patterns of traits associated with them can differ significantly from traits located on non-sex chromosomes (autosomes).

For example, many sex-linked traits, such as hemophilia and color blindness, are located on the X chromosome. This leads to unique inheritance patterns, especially in males, who have only one X chromosome. If a male inherits an X chromosome carrying a recessive trait, that trait will be expressed, as there is no corresponding allele on the Y chromosome to counter it. In females, who possess two X chromosomes, a similar trait may only manifest if both Xs carry the allele for that trait.

The other options describe concepts that do not specifically pertain to the nature of sex-linked traits. Traits influenced by environmental factors, traits influenced by dominant alleles, and those that can be inherited from either parent incorporate broader genetic principles but do not accurately define sex-linked traits' unique relationship with the sex chromosomes.