Here's why:

* Sex chromosomes: These are the chromosomes that determine an individual's sex. In humans, females have two X chromosomes (XX) while males have one X and one Y chromosome (XY).

* Inheritance: Genes located on these sex chromosomes are passed down from parents to offspring in a specific way.

* Examples of sex-linked traits:

* Red-green color blindness: This is more common in males because the gene responsible for normal color vision is located on the X chromosome. Females have two X chromosomes, so they can have a "backup" copy of the gene.

* Hemophilia: This is a bleeding disorder also linked to the X chromosome.

Let me know if you'd like more information on sex-linked traits!