My son has lots of freckles on his face and arms, and he recently asked me why. I had no idea! Can you tell us? – Bran
Freckles tend to run in families. People (especially kids) who have fair complexions are most likely to freckle.
People with light skin and eyes have less melanin, a chemical in the skin that protects it from sun damage by reflecting and absorbing ultraviolet (UV) rays, but some melanocytes (the melanin-producing cells) make more melanin when exposed to the sun. Instead of tanning evenly, people with less melanin get freckles.
So it's a combination of genetics and sun exposure that explains why your son has freckles. Some people's freckles fade away almost completely in the winter, just to return in the summer. People who freckle are often more likely to get sunburns. It is important for everyone (freckled or not!) to wear sunscreen while outside to protect against skin damage and skin cancer.