Type 2 diabetes has a stronger link to family history and lineage than type 1, although it too depends on environmental factors. Studies of twins have shown that genetics play a very strong role in the development of type 2 diabetes. Lifestyle also influences the development of type 2 diabetes. Obesity tends to run in families, and families tend to have similar eating and exercise habits.
If you have a family history of type 2 diabetes, it may be difficult to figure out whether your diabetes is due to lifestyle factors or genetic susceptibility. Most likely it is due to both. However, don't lose heart. Studies show that it is possible to delay or prevent type 2 diabetes by exercising and losing weight.