It’s a question even the most brave and crude would struggle to type into Yahoo! Answers: Why is it our genitals and nipples are darker than the rest of our skin? Speaking to the Daily Mail Online, Dr. Cameron Rokhsar and Dr. Lindsey Bordone – both dermatologists based in New York – answered this age-old question. Turns out, it’s all to do with our sex hormones. The level of hormones present in our body, such as testosterone and estrogen, regulate the activity of our melanocyte cells. These are the cells in our skin and hair that release melanin, the protein pigment responsible for our skin color. Production of these ramp up when we hit puberty, hence why these dark areas only appear to emerge when we get older. “Hormones regulate the way melanocytes produce their pigment," said Dr. Rokhsar. "Those can have an effect on the way the skin in that area pigments, so generally that area is darker." “When girls are young, their nipples are light,” Dr. Bordone added. “And as they get older, hormones have an effect and the nipples darken. “It’s very similar for boys.” This is also the reason why so many kids have fair hair, yet grow up to have darker locks. According to Dr. Bordone, although dark sexy bits are usually a normal characterstic, a change in color could be a sign of health problems, such as diabetes. “Your skin can darken in certain areas when your sugars are very high – and you’re developing diabetes,” she said. Chances are it's nothing to worry about, but if you’re unsure you should consult your doctor. Source
