If you think you’re safe from hair loss by virtue of being in your 20s, think again. Genetics and hormones, and not age, dictate your hair’s health and life span. Over 25% of men in their 20s suffer from male pattern baldness, with the number increasing to 50% for men in their 40s. Thinning of hair and the eventual hair fall are largely due to the male hormone, testosterone, interacting negatively with hair follicles on the top of your head.