Having genes that give you red hair, pale skin and freckles increases your risk of developing skin cancer as much as an extra 21 years' exposure to the sun, researchers said Tuesday.

Their study found gene variants that produce red hair and freckly, fair skin were linked to a higher number of mutations that lead to skin cancers. The researchers said even people with one copy of the crucial MC1R gene — who may be fair-skinned but not have red hair — have a higher risk.

"It has been known for a while that a person with red hair has an increased likelihood of developing skin cancer, but this is the first time that the gene has been proven to be associated with skin cancers with more mutations," said David Adams, who co-led the study at Britain's Wellcome Trust Sanger Institute. "Unexpectedly, we also showed that people with only a single copy of the gene variant still have a much higher number of tumor mutations than the rest of the population."