Hair loss isn't always due to an illness or a medical condition. Many men have male pattern baldness. Women can get pattern baldness, too, but it is not as common. This runs in families and usually comes from the mother's side of the family. If you want to know if you are likely to go bald in the future, look at your mother's father to get your best guess.
Hair has a limited life span.
Each hair usually lives about four to five years and then falls out. A new hair then starts to grow. In male pattern baldness, when a hair falls out, a new one does not start to grow. This usually happens above the forehead, giving the familiar receding hairline look. It also happens at the crown of the head.