obesity occurs in families according to a clear inheritance pattern caused by changes in a single gene. The most commonly implicated gene is MC4R, which encodes the melanocortin 4 receptor. Genes give the body instructions for responding to changes in its environment. Studies of resemblances and differences among family members, twins, and adoptees offer indirect scientific evidence that a sizable portion of the variation in weight among adults is due to genetic factors.
I hope this helps
