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Your parents may have told you that every freckle on your face was a kiss from an angel, but SciShow is here to ruin that delusion for you.

Hosted by: Hank Green
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Sources:

http://www.ncbi.nlm.nih.gov/pubmed/2071942
http://www.ncbi.nlm.nih.gov/pubmed/25155575
https://ghr.nlm.nih.gov/gene/MC1R
http://genetics.thetech.org/ask/ask195
http://www.medicinenet.com/freckles/article.htm
http://www.livescience.com/32478-why-do-we-get-freckles.html
If you're a freckly person, your parents might have told you as a kid that every freckle was a kiss from an angel, or maybe that your freckles were the stars of the night sky sparkling on your cheeks. Which is all very sweet, but I don't think it will come as a shock to you if I tell you that your freckles are not stars so hopefully no one has ever tried to draw constellations on your face. Instead, freckles are small areas of the skin that contain higher amounts of melanin, the pigment protein that is responsible for our eye, skin and hair color. And melanin is good. It's produced by skin cells called melanocytes and acts as a natural sunscreen, darkening your skin and protecting you from the Sun's dangerous UV rays.

In some people melanin is produced evenly throughout the skin, but for freckles to appear melanin forms in little clumps, which get darker when exposed to sunlight. But those spots fade when they're exposed to less sunlight, like in winter. So nobody is born with freckles exactly. Instead, they appear after spending some time in the sun. And freckles can look very similar to another feature of the skin called lentigines but they're not the same thing. 

In lentigines, the skin contains more melanocyte cells and those cells aren't going anywhere, so lentigines normally don't change that much depending on your exposure to sunlight. It's not completely understood what's responsible for either of these kinds of spots but we know freckles are linked to a key genetic player in regulating your skin and hair color, a gene known as MC1R.

This gene controls how much of which kind of melanin you produce, and you actually have two main types, darker brown eumelanin and reddish yellow pheomelanin. If you have an active MC1R gene, then your body produces more eumelanin leading to darker hair and skin that protects against the sun. If that gene is inactive then you'll produce more pheomelanin leading to fairer skin, blonde or red hair and a propensity for freckles. But not all people with red hair have freckles and not all freckled people have red hair. Even thought the traits are thought to be controlled by the same gene it turns out that red hair is a recessive trait while freckles are a dominant trait.

So there are likely more genes at work here than just MC1R. The fact is, scientists are still trying to understand how all of your genes combine to determine the many traits you're showing off right now. 

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