Most people with EB have inherited it through mutations in genes from their parents. Everyone has two copies of most genes: one copy from their mother and one from their father. Genes are in the body’s cells and determine inherited traits such as eye color and dimples. They also govern some bodily functions, such as the formation of proteins in the skin. EB is caused by the abnormal formation or absence of these proteins. More than 10 genes are known to affect the formation of proteins in the skin. The type of EB someone has depends on which of these genes has a mutation and which protein has not been formed correctly.