The blame is something that we can and should take steps as a society to address. It doesn't help, and ironically it's the same society that created a situation where a tremendous number of people are developing diabetes then turns around and blames the individual for it.
I will not accept though that the next generation is genetically doomed, and the next even more so, to have an ever increasing prevalence of diabetes. I believe there are steps we can take that would have positive effects in terms of how many people, whether genetically predisposed or not, will develop type 2 diabetes (and type 1 and many other diseases for that matter). Among those steps I think that eating healthier foods... Including a major reevaluation by society as a whole about what actually constitutes 'healthy food' and encouraging more physical activity would be high priorities.
Because someone is genetically predisposed to a condition does not mean that they can't take steps to improve their odds. Alcoholism is a fantastic example. You can genetically be predisposed to alcoholism but you can take steps to absolutely ensure you are never stricken by the disease...
We are currently living in a world that evolution has not prepared our bodies for. There is nothing in our history that prepared human beings to sit at computers for 12 hours / day at work, to eat grains ground to a pulp then reconstituted, to eat the majority of our calories from highly refined carbohydrates, etc.
I believe that many diseases are preventable, including the majority of diabetes-- but it will take more than one person making good choices, it will take an entire cultural shift of direction to have a meaningful effect. Part of that cultural shift is to stop blaming, start understanding that we are all part of the culture that has gotten us here, and coming together to make changes.