Get the answer of: Is Baldness an Example of Sex-Linked Genes?
No, baldness is not an example of sex- linked genes. But it is an example of sex- influenced genes.
It may occur in some cases, due to disease or other environmental factors, but is of generally a hereditary character, which is more prevalent in men, than in women. Studies on the mode of inheritance of baldness have shown that it is not inherited in the same way as the recessive sex-linked genes.
It cannot be due to a dominant sex-linked gene, because more women than men are not bald. It has been shown that baldness is due to peculiar genes, called sex-influenced genes. The character is dominant in men and recessive in women.
A man is bald if he has only one gene for baldness, but a woman is bald if two genes are present. If ‘B’ presents a gene for baldness and ‘b’ for non-baldness, and the sex- influences is such that ‘B’ is dominant in man, and recessive in woman, the genotypes of various individuals will be :
However, baldness may be purely due to environmental factors, or due to certain diseases, e.g. syphilis, seborrhoea or thyroid diseases. Horns of sheep and spotting in catties are also the sex-influenced characters.
Gene ‘B’ behaves as a dominant in males and as a recessive in females, appearing to exert its effect in the heterozygous state only in the presence of male hormone. A number of reports in the literature dealing with abnormalities leading to hormone imbalance or with administration of hormone, support this view.