1. Family History (Heredity)
This is the key cause for most male or female pattern baldness. It normally happens as age increases. For men normally a receding hairline and thinning of hair in women.
2. Hormonal Changes and Medical Conditions
There are a variety of conditions that may cause permanent or temporary hair loss, such as pregnancy, childbirth, menopause or thyroid conditions.
3. Medications and Supplements
Certain drugs can have side effects that cause hair loss. This includes medications for cancer, arthritis, depression, heart problems, gout and high blood pressure.
4. Radiation Therapy
Radiation therapy is a way of treating cancer patients. It is widely known that those who get treated by radiation would lose hair slowly and though it grows back, it would be very different than it used to be.
Emotional or Physical high-stress situations in recent times can cause a person to have thinning of hair. This is normally temporary only.