Discovering the genetics of hair loss
The Genetic Blueprint of Male Pattern Baldness
When hair loss is primarily driven by genetics, it tends to follow characteristic patterns — known as male pattern baldness (MPB) or female pattern baldness (FPB) — distinguished by where and how hair thins over time.
For men, male pattern hair loss or MPB often begins with a receding hairline at the temples, forming an M-shaped pattern, and may progress to thinning at the crown. This type of hair loss can start as early as the 20s or 30s, with studies showing that 80% of men experience some degree of MPB by the age of 80 [2].
The medical term for both MPB and FPB is androgenetic alopecia, and it is the most common cause of hair loss worldwide. Research into twins has revealed that genetic prediction of male pattern baldness accounts for about 80% of the likelihood of developing MPB, underscoring the importance of hereditary factors [2]. However, hormonal changes, particularly related to androgens, and lifestyle factors such as stress and nutrition also play critical roles in the development and progression of hair loss.
X Marks the Spot: Will I go bald if my mother's father was bald?
It’s a common myth that baldness is inherited solely from your maternal grandfather, but this isn’t entirely accurate. While there is some truth to the idea that male pattern baldness is influenced by genes on the X chromosome inherited from your mother, this is only part of the story.
The genetics of MPB are complex and thought to be polygenic, meaning that multiple genes are involved rather than a single dominant gene. Everyone has 23 pairs of chromosomes, with one pair — the X and Y chromosomes — determining biological sex. Men inherit their X chromosome from their mother and their Y chromosome from their father [3].
The androgen receptor (AR) gene, located on the X chromosome, is strongly associated with male pattern baldness [4].
Research involving over 12,000 men of European ancestry found that those with certain variations in the AR gene were more than twice as likely to experience MPB [5].
However, this isn’t the only gene involved in baldness. A 2017 review identified 63 genetic variants linked to male baldness, with only six of these found on the X chromosome [6]. The majority of these genes are located on autosomal chromosomes, meaning both parents can pass on the genetic predisposition for hair loss.