The Genetics Of Balding From Either The Mother Or Father

Estimates suggest that more than 80% of cases of male pattern baldness are hereditary. It is a polygenic trait and can be inherited through either side of a family, or it may come from both sides. Depending on a person's genetic make-up, hair loss of this type can begin any time after puberty.

A Key Gene Can Come From A Maternal Grandpa

The most influential hair loss gene is carried on the X chromosome, which a male would only get from his mother, and which could have been passed on by her father.

Men only have one X-chromosome, which they get from their mothers. Their other sex chromosome is a Y-chromosome, received from their fathers. The gene variant for baldness is believed to be recessive, so in women, who have two X-chromosomes (one from their father and one from their mother), the baldness is very rarely expressed. Men, however, have no second X-chromosome. If they get the baldness variation from their mother's X-chromosome, that recessive quality will come out in full force. Presto! Baldness.

The Genetics Of Balding From Either The Mother Or Father

So the bottom line is that even if your grandpa has managed to hold onto a full head of hair his entire life, there's still a reasonable chance you might lose some of yours. It may account for bald men taking after their maternal grandfathers, but baldness is also often passed from father to son.

Inherited Baldness Among The Men

Two new studies have fingered a small region on chromosome 20 called 20p11 is closely associated with inherited baldness among the men. The chromosome, one of the bundles of DNA in every cell that contain the genes, can be inherited from either the mother or father.

The variants gene provides instructions for making a protein called an androgen receptor. Androgen receptors allow the body to respond appropriately to dihydrotestosterone and other androgens. Studies suggest that variations in the variants gene lead to increased activity of androgen receptors in hair follicles. It remains unclear, however, how these genetic changes increase the risk of patterned hair loss in men and women with androgenetic alopecia.

This sort of thing could explain people who are bald even though their mom's dad still has a full head of hair.

An estimated 14% of men are thought to carry the two chromosome 20 variants. If you have both the risk variants on chromosome 20 and the unrelated known variant on the X chromosome, your risk of becoming bald increases sevenfold.