“Why are men more likely to be colorblind than women?”
Men have an X and a Y chromosome and women have two X chromosomes. The gene for colorblindness is on the X chromosome. Colorblindness is a recessive allele, which means that the dominant trait (normal vision) will mask it if you have one dominant and one recessive chromosome. Women can have either one dominant and one recessive chromosome, two dominant or two recessive. Therefore, the only way they can be colorblind is if they have two recessive chromosomes.
Men, on the other hand, have an X and a Y chromosome. This means that their colorblindness is determined on the basis of whether their X chromosome is recessive (colorblind) or dominant (normal vision). Because their Y chromosome doesn’t carry the colorblindness gene it cannot mask the recessive chromosome. That is why men are more likely to be colorblind than women.