There are two main types of skin cancer. Non-melanoma skin cancer is the most common type of cancer in the U.S. The National Cancer Institute predicts more than one million new cases in 2009. Ultraviolet radiation from sun exposure is a primary risk factor for skin cancer. Melanoma, a skin cancer that forms in cells that give our skin color, is the sixth most common type of cancer, especially among 25 to 29 year olds, and causes most skin cancer deaths.

Having a family history isn't the most significant risk factor for skin cancer; however, it does increase your likelihood of developing it. Researchers are still studying why, but here's what they know now.

The Role of Genes

In some families, genes for light skin and freckles increase your risk for melanoma with unprotected sun exposure. In other families, members pass along specific gene mutations implicated in skin cancer. If you have two or more first-degree relatives (parents or siblings), more than three blood relatives, or a family member with more than one original melanoma, you are more likely to develop melanoma, often at a young age. A family history of pancreatic cancer also increases your risk for melanoma.

Recently, researchers found that having two mole-influencing gene variants doubles your risk for developing melanoma (more moles increases your risk). We inherit one gene from each parent. If you carry one variant, your risk for melanoma is 25 percent greater than someone who doesn't have the variation; having both variants doubles your risk.

Scientists have also found two genes (with two variants) linked to basal cell carcinoma (BCC), the most common type of non-melanoma skin cancer. If you inherit both variants, you are three times more likely to develop BCC. And, if you have three additional genetic changes linked to cancer, your risk for BCC is 12 times higher.

Is Genetic Testing Useful?

Genetic testing for skin cancer is controversial. Science hasn't identified all the genes linked to skin cancer, so physicians fear giving patients a false sense of security from a genetic test result. Furthermore, in addition to genes, other factors also influence risk.

Bottom Line

Having a family history does not mean you will get cancer. Less than 10 percent of people with melanoma have a family history. If you're at greater risk for melanoma or non-melanoma skin cancers due to family history, see a dermatologist regularly and be diligent about self-exams. Your best bet for preventing skin cancer is to avoid excessive or unprotected sun exposure and tanning beds.