Are there some genetic reasons i get aphthous stomatitis off and on?

Probably not, but...: If the reason for your aphthous ulcers are canker sores, then you may have acquired the infectious agent that causes the sores from a family member, but genetic predisposition is unlikely. However, if your aphthous ulcers are secondary to crohn's disease, then the answer is maybe. About 15% of close relatives of crohn's patients carry genes that predispose for this inflammatory bowel disease.

Possibly: The cause of aphthous stomatitis (canker sores) is unknown, but the disease has been linked to genetic, nutritional and immunological triggers as well as bacterial infections. People with recurrent lesions may have iron, folic acid, and certain b vitamin deficiency. There is evidence that genetics can modify the risk of recurrent sores, many with this condition have a family history of recurrence.