Family history
Besides gene mutations, family history also plays a role in the development of melanomas. If you have a close relative (parents, siblings) who has had skin cancer, you are more likely to get melanoma.
This is probably partly because all living organisms tend to share the same type of genes as our parents and close relatives.
Many families tend to have rare (atypical moles) or large numbers of moles. The atypical moles appear to have a different color or shape and may be larger than usual. These also tend to become (malignant) cancerous. But most of the atypical moles don’t become cancerous. Individuals with such atypical moles have a melanoma risk that is higher than average.
Researchers have found that FCS (family cancer syndrome) will increase your risk of developing melanoma. Those that have FCS over fifty usually have more than 50 moles, and a minimum of one close relative has already been diagnosed with skin cancer. This relative can be a parent, brother, sister, child, aunt, or uncle. Some families with family cancer syndrome are also at a higher risk of developing carcinoma of the pancreas.
Scientists believe that about 1 in 10 cases of melanoma (10%) may be associated with inherited defective genes. It is known that a gene called CDKN2A triggers family cancer syndrome. Sun protection is even more important for the small number of families carrying these genes.