Male pattern hair loss is caused by a combination of genetic, hormonal, and environmental factors.
Your genes, inherited from both your parents, determine your sensitivity to hormones called androgens, particularly one called dihydrotestosterone (DHT).
Each strand of hair begins in a hair follicle and normally grows for two to six years before going into a resting phase and falling out.
When the follicle begins to grow a new hair, the cycle starts again.
Increased androgens in the hair follicles can lead to shorter cycles of hair growth, lasting just weeks or months.
DHT stimulates the process of miniaturization, which causes new hairs to grow shorter and thinner than before.
Eventually, the hair follicles become too small to produce new hairs.