SKIN COLOUR GENETICS   further to our discussions in class...

There are at least three ways people can end up with different skin color. One way is if people make less pigment. Less pigment = lighter skin.

Another way is when people have fewer melanocytes. Fewer melanocytes mean less pigment overall and so lighter skin.

The third way has to do with the kind of pigment someone makes. There are two types of melanin. Eumelanin is black or brown pigment and pheomelanin is red or yellow pigment.

People who make lots of pheomelanin tend to have lighter skin, often because of freckling. 

Melanocytes are usually spread pretty evenly in the skin. So when freckles form, some spots of the skin have lots of melanocytes (freckles) and other spots have few or none. Where there are no melanocytes, the skin is very fair.

Skin Color Genes

Scientists have figured out that several genes are involved in skin color. One of these genes is the melanocortin 1 receptor (MC1R).

When MC1R is working well, it has melanocytes convert pheomelanin into eumelanin. If it's not working well, then pheomelanin builds up.

Most people with red hair and/or very fair skin have versions of the MC1R gene that don't work well. This means they end up with lots of pheomelanin, which leads to lighter skin.