While it’s primarily genetic, there's no strict rule to determine who is going to lose their hair.
The exact trigger for male-pattern baldness is a hormone called dihydrotestosterone (DHT). This is found naturally in the body but if you’ve inherited a sensitivity to DHT in your hair follicles this will lead to the overall weakening of hair growth.
But lifestyle factors can also contribute to hair loss.
Your emotional health and wellbeing, diet, level of sleep and some medications can all exacerbate hair loss in anyone with a genetic sensitivity.