Question

Both men and women can be colorblind, but there are approximately 100 times more colorblind men than women in the world. Explain why men are more likely to be colorblind than women.

Answer 1

Color blindness is an X-linked trait. This means that the gene that decides whether or not someone is colorblind is found on the X chromosome. X and Y chromosomes are the chromosomes that decide biological gender. Females have 2 X-chromosomes and males have 1 X and 1 Y-chromosome. Colorblindness is also a recessive gene; this means that for colorblindness to present itself, it must be the only type of gene present. So, if there is a dominant, non-colorblindness allele, then the person will not be colorblind.

Since men only have 1 X-chromosome, if that chromosome has the recessive trait, they will be colorblind. On the other hand, women have 2 X-chromosomes. Therefore, if either of these chromosomes has the dominant allele, then they will not be colorblind.

In the end, the reason why men are more likely to be colorblind is because of probability, and the fact that they do not have the safety of 2 chances like women.