The usual and most common cause of hair loss seen is called Androgenetic alopecia. It is also widely referred to as Male Pattern Baldness (MPB) or Female Pattern Baldness (FPB). MPB or hair loss occurs due to Dihydro Testosterone (DHT), a testosterone derivate. And some males are genetically more sensitive to DHT.
Men have much higher levels of testosterone hormone (hence DHT as well) compared to women. That is why men more affected by androgenetic alopecia.