Final answer:
Colorblindness is typically inherited as an X-linked recessive trait. A woman can be colorblind if she inherits two X chromosomes with the colorblindness gene. Men are more likely to be colorblind because they have only one X chromosome and the condition is expressed if they inherit the gene.
Step-by-step explanation:
Colorblindness is typically an X-linked recessive trait, which means the gene causing colorblindness is located on the X chromosome and is recessive. There are three main types of color blindness which are red-green (most common), blue-yellow, and total color blindness. Red-green color blindness itself includes two different types: protanopia (lack of red photoreceptor pigment) and deuteranopia (lack of green photoreceptor pigment).
The Law of Dominance states that in a pair of alleles, the one that is dominant wholly masks the effect of the allele that is recessive, in the organism's phenotype.
Regarding inheritance, a woman can be colorblind if she inherits two X chromosomes with the colorblindness gene, or one X chromosome with the gene if her other X chromosome is inactive or missing. If a woman is colorblind and her sister is not, it indicates that their mother is at least a carrier of the gene and their father might not have the gene for colorblindness.
Male sex chromosomes are XY and female sex chromosomes are XX. Because the Y chromosome comes from the father, he determines the sex of the child. Since men have only one X chromosome, if they inherit an X-linked recessive gene for colorblindness, they will exhibit the condition. Conversely, a son cannot inherit colorblindness directly from his father because he inherits his father's Y chromosome, not his X.
For a female to become colorblind, she must inherit two genes for colorblindness, which is rare because it requires both her mother to be a carrier and her father to be colorblind or a carrier. Unaffected daughters may carry the gene, while affected sons have inherited the recessive allele for the trait from their mothers.
Lastly, the prevalence of red-green color blindness varies among different populations, with approximately 8% of males of European Caucasian descent affected, while it is less prevalent among other populations.