The genetic components of hair loss have not been fully realised but the knowledge of what exactly is going on has increased. Current research is showing that for male pattern baldness is largely x -linked (females have two x chromosomes, while males have one X and one Y).
Researchers have indicated that the Androgen Receptor Gene (AGA) is required for hair loss to occur to the level for it to be an issue, there is a specific variant of AGA for the baldness to develop. This have been confirmed my multiple research groups. The AGA gene is recessive (this means that a females needs the mutation in both X chromosomes to show male pattern alopecia), this already shows that the chance of a female getting baldness is already significantly less. The next most like culprit is a gene which resides on chromosome 20.
Other researchers have found that the region Xq11-q12 on the X chromosome is likely to be implicated. Specifically within this there is a gene called Ectodysplasin A2 receptor (EDA2R). Another gene that has been implicated is on chromosome 3 and is located at 3q26. This gene is also involved in mental problems as well as baldness, it is also recessive.Another potential rogue gene is P2RY5. This gene has a role in the structure of hair. With less desirable variants of this gene causing baldness at birth, and other causing wooly hair (hair that appears tightly coiled under the microscope).
Different variants of this gene are linked to hair loss. Bad mutations in this gene can lead to loss of teeth, sweat glands and hair. The protein from this gene binds to EDA-A2.
During the a of over 500,000 locations on the human genome a genetic variant was found which happened more in bald men than in the control group. 300 bald men were included in this. Two regions were found to be more associated with the hair loss. One was in the region of the androgen receptor, the other was found to be on chromosome 20 which can come from either the mother or the father. Reference