Hair loss, medically known as alopecia, is a commonly diagnosed disorder. The most common cause of hair loss is androgenic alopecia. It’s a process driven by genetics and hormones that causes hair follicles to become smaller over time. As a result, new hair may appear a little thinner or more delicate. This typically begins with subtle changes around the temples or a thinning spot at the top of the head. While some might notice these changes during their late teens, others may not see any shifts until much later in life.