The most common type of hair loss in men is ‘male pattern baldness’, or androgenetic alopecia, which is the cause of 95% of hair loss in men. It usually starts from around the age of 30, but can occur any time after puberty. How quickly baldness develops, and the pattern of hair loss, is probably genetically determined. It usually begins with thinning at your hairline, usually seen as an M shape, followed by a thinned or bald spot on the crown of your head.