no one is lean in my family up to 3 generations. We are all vegetarians, BUT eat lots of rice and use good amount of cooking oil in food prep. Grand parents [medical docs and very physically active till death] got T2D at 80+ years of age, did not suffer much. Parents [school teachers, not that physically active]got early, and they suffered a lot.Obesity is not hereditary. Although it's possible eating/cooking habits are passed on.