Genetics is involved in the development of autoimmune disease, but autoimmune diseases are not typical genetic diseases. Within families that are susceptible to autoimmunity, one family member may have lupus, another family member may have Sjogren's disease, a third member of the family may have rheumatoid arthritis.
Environmental factors account for around half of autoimmunity susceptibility. Few of the environmental triggers are known. Certain drugs can induce lupus. Certain environmental substances like silica that can induce scleroderma. It is suspected that there are certain dietary substances, such as iodine, that can exacerbate thyroid disease.