Causes 

It is due to combination of hormones (androgens) and a genetic predisposition

Male pattern hair loss is a hereditary condition, dihydrotestosterone (DHT) which is an active form  of male  sex hormone is responsible for MPHL.

 DHT shortens the stage of growth period  (anagen phase) of the hair cycle, from a span  of 3–6 years to few weeks or months .This takes place with scarcity of the follicles which gradually progresses producing fewer and finer hair.

 In some women increased levels of androgens with a positive family history presents with male pattern hair loss. These women also appear with acne, inconsistency in menses and excessive hair on the body and face. These are peculiar   features of polycystic ovarian syndrome (PCOS) though most of the women with PCOS do not present with hair loss.

Role of heredity/genetics in the male pattern hair loss

Heredity/Genetics plays an important role in MPHL as the it takes place in men who are genetically more sensitive to the effects of DHT. It can be inherited from either side of maternal or paternal family.

How common is male pattern hair loss?

Male pattern hair loss represents itself in all men at some or the other point in their lives. Certain amount of hair loss is seen by the age 50, and possibly 80% by the age of 70 years.

Is hair loss just a cosmetic issue?

Male pattern hair loss can have a negative impact on the psychology of a person. It is also correlated with self-doubt, depression, insecurity , and feelings of unhappiness