Interesting. Because one of the X-chromosomes is inactivated in female cells (which have XX). Otherwise it would lead to over expression of X-chromosome Genes

Interesting. Because one of the X-chromosomes is inactivated in female cells (which have XX). Otherwise it would lead to over expression of X-chromosome Genes (well most anyway).[1] [1]https://ghr.nlm.nih.gov/chromosome/X https://ghr.nlm.nih.gov/chromosome/X (There are some genetic disorders where an organism have 3 of one chromosome. Trisomy its called.) Which X is inactive is somewhat random however so it seems that it reduces the instance of color blindness.