
What causes freckles on the human body?
Freckles are formed when groups of melanocyte cells beneath the skin are triggered by sunlight to increase melanin production.
Asked by: Sophie Webber, by email
Freckles are formed when groups of melanocyte cells beneath the skin are triggered by sunlight to increase melanin production. A regulating protein on the cells (called MCR1) is responsible for controlling this process. People who get lots of freckles have a variant of the protein that encourages greater production. The protein is coded by a dominant gene, which means that people who have freckles are highly likely to produce children who also get freckles.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
Authors
Sponsored Deals

January sale subscription offer!
- Try 3 issues of BBC Science Focus Magazine for just £5
- Risk - free offer! Cancel at any time when you subscribe via Direct Debit.
- FREE UK delivery.