Most skin cancer is caused by ultraviolet (UV) light damaging the DNA in skin cells. The main source of UV light is sunlight.
Sunlight contains three types of UV light:
UVC is filtered out by the Earth's atmosphere. UVA and UVB damage skin over time, making it more likely for skin cancers to develop. UVB is thought to be the main cause of non-melanoma skin cancer.
Artificial sources of UV light, such as sun lamps and tanning beds, also increase your risk of developing skin cancer.
Repeated sunburn, either by the sun or artificial sources of light, will make your skin more vulnerable to non-melanoma skin cancer.
In most cases, non-melanoma skin cancer doesn't run in families. However, research has shown that some families have a higher than average number of members who develop the condition.
For example, if you have a parent who's had squamous cell carcinoma, your risk of also getting it is two to three times higher than average.
Certain factors are thought to increase your chances of developing all types of skin cancer.
The Cancer Research UK website has more information about skin cancer risks and causes.