How do freckles develop?
Freckles are thought to develop as a result of a combination of genetic tendency (inheritance) and sun exposure. Two people receiving the same sun exposure may not have an equal chance of developing freckles. Natural sunlight and artificial suntanning lights emit ultraviolet (UV) rays. After exposure to ultraviolet rays, the outer layer of the skin (the epidermis) thickens and the pigment-producing cells (the melanocytes) produce the pigment melanin at an increased rate. (This production of melanin may in fact give some protection against future sun exposure.) Of course, people differ a great deal in their reaction to sunlight. To take an extreme example, there is no pigmentation in the skin of an albino because of a defect in melanin metabolism. On the other hand, people with dark complexions are relatively less sensitive to sun exposure than fair-skinned people. However, people with dark skin are not entirely resistant to the effects of the sun, and they, too, can become sunburned wi
