There appears to be three general categories of causes for excess hair:
Congenital: Normal racial and familial growth patterns.
Everyone comes into the world with some pre-established pattern for hair growth “built-in”. This pattern is inherited from parents whose own genetic structures combined to shape the new one.
Topical: This is exactly what the word implies, local, limited to the skin or particular portion, such as rubbing, chafing, burning or other causes of irritation.
While nature has provided the body with an ingenious means of defending itself, sustained irritation almost always stimulates hairs in the immediate vicinity of the affected area to grow deeper and coarser, thereby creating a mat of hair that covers the skin and protects against further irritation. This can cause an increase blood supply to the surface of the skin. When increased blood supply reaches the follicles, any hairs growing from those follicles receive more nourishment than usual. Therefore they tend to grow deeper and coarser. This is where plucking, tweezing, and waxing comes in and what the person does not realize is the fact that repeated epilations eventually cause most hairs to regrow more quickly and to become darker, coarser and more firmly rooted. Thus, the person who tweezes is simply letting herself in for greater hair problems than they had before they tweezed; rather than solving the problem, it is worsening it.
Systemic: Lastly, all growths which are neither congenital nor topical are considered “systemic”.
To appreciate how body chemistry can effect the hair growth, one must have a rudimentary understanding of the endocrine system. Hormones, which are excreted by the endocrine glands, control the growth and development of every organ of the body, including the hair. The interrelationships of the glands are so complex, however, that scientists have only begun to understand the total mechanics of the endocrine system.
Another cause for growth of facial hair can be abnormal systemic changes that are related to an endocrine imbalance. This usually requires a qualified physician or endocrinologist to diagnose.
When you see your electrologist for the first time, they may ask a series of questions to analyze your hair growth patterns and may suggest a visit to the doctor to rule out and/or treat hormonal issues as you undergo your electrolysis treatments.
Information referenced from the Electrolysis Society of Alberta: http://www.onlineesa.com/ and Electrolysis Thermolysis and the Blend: The Principles and Practice of Permanent Hair Removal by Arthur Ralph Hinkel