Are there some genetic reasons I get sepsis off and on?

Some people are more vulnerable than others to infection (due to deficiencies in ige, or iga, etc) or, when they become infected have an inability to fight off infection due to either a problem with their white blood cells, their ability to form an immune response, an autoimmune disease, etc.

All of these have a genetic component... But you should see an immunologist regardless.

Some people are more resistant to sepsis than others.

Genetics are suspected of playing a role, but this is a matter that is very poorly understood at this time.