Type II is definitely of genetic origin although there may be up to 10 different genes involved.
The number of adults diagnosed with Type II is consistent with the number of adults identified as having the suspect genes.
You are not going to "catch" diabetes. Type I has several causes ~ but only one source of injury ~ the loss of insulin production in/near the pancreas/liver complex. Some folks with Type II will discover that it can turn into Type I over time.
Type II diabetes is associated with obesity and with aging. It is a lifestyle-dependent disease, and has a strong genetic component (concordance in twins is 80-90%). The problem seems not so much in insulin production,but that when the insulin reaches its target cells, it doesn't work correctly.Most Type II diabetes patients initially have high insulin levels along with high blood sugar. However, since sugar signals the pancreas to release insulin,Type II diabetics eventually become resistant to that signal and the endocrine-pancreas soon will not make enough insulin. These people end up managing the disease with insulin and they need much higher doses because they are resistant to it.
Genetic component, yes, but also a lifestyle component.