How does sex-linked inheritance work?
Sex-linked inheritance is exhibited by traits whose genes are located on sex-chromosome or X chromosome.
The inheritance of genes located on sex chromosome or X chromosome follows different pattern as compared to that of genes located on autosomes.
In human beings , sex is determined by a pair of chromosomes called sex chromosomes, having XY mechanism. The male is heterogametic (XY) and the female is homogmetic (XX). Thus the genes present on sex chromosome in females are in double doze just the same way as genes present on autosomes. But in male, the genes present on X chromosome are in single doze as Y chromosome does not carry homologous genes to those on X chromosome.
The sex-linked genes show cris-cross pattern of inheritance, i.e. the genes present on x chromosomes of male are never transferred to male offsprings of the first generation, but to females only. The genes inherited from male parent by the female are passed on to 50% of male progeny of next generation.
This cris-cross pattern of inheritance is termed sex-linked inheritance.
Common examples of sex-linked inheritance in human beings are Hemophilia and color blindness.