Freckles on the face are often associated with youthfulness. Aside from the tops of the cheeks and nose, freckles can appear anywhere on the body as small, circular spots that are a shade or two darker than the person's natural skin color. Often these are mistaken for moles or birthmarks. But why do they occur only on some people and not others? And why do they sometimes more noticeable after sun exposure?
Like many physical traits, the appearance of freckles is influenced by genetics. In particular, scientists have pinpointed one gene, the MC1R gene, that provides the instructions for making the pigment protein melanin that gives color to the skin and hair. Inactivity of the MC1R gene causes the production of phenomelanin, which leads to fairer skin, hair, and freckles.
But many other factors, genetic and environment, contribute to how melanin is expressed on our bodies. Sun exposure, for example, can definitely trigger melanin production, which can cause freckles to appear. Other genes and genetic modifiers are likely at play too, as not all fair-skinned, red-haired people have freckles, while some dark-skinned, brown-haired do have these spots. Freckled or not, experts agree that sun protection is necessary for everyone, so don't skimp out on your SPF!