The skin protects itself from strong solar radiation by producing increased amounts of brown melanin pigments. However, the skin of individuals with blond or red hair does not brown evenly. Instead, small brownish spots-known as freckles-are formed. Just as with hair any eye color, freckles are a genetically determined feature. Several genes are responsible for how much melanin pigment is produced and how it is distributed in the skin cells.
Freckles can become paler when there is little solar radiation, or be minimized with the help of bleaching cream, but they do not disappear altogether. Even after laser therapy to destroy pigment cells, new freckles will reappear eventually. Hormonal changes during pregnancy can often cause freckles to darken, but pigment production usually returns to normal after giving birth.