I'm wondering to what extent, if any, these studies have taken epigenetic influences into account. Epigenetics points out that there are more genetic factors in play than the basic coding of our DNA. The effects of a "bountiful year", and resulting increases in fat, cause epigenetic changes that can affect the next generation. I believe one of the studies upon which this is based involved a population in Greenland, but I'll have to confirm that. The basic premise is that, by overeating yourself, you can pass the tendency towards obesity on to your children, through epigenetic markers that control the activation/deactivation of specific genes. It's an interesting field of study that explains how genetic factors can have significant immediate affect, without any underlying gene mutation. It could be one of the reasons we see rapidly increasing genetic tendencies towards obesity, and it suggests that the adoption of a healthy lifestyle, even if it means working really hard to do so by fighting your own genetic tendencies, can benefit your offspring not only by setting an example, but by passing on appropriate epigenetic markers.

One thing that is, IMO, indisputable, is that efforts to combat obesity need to focus on the early ages. Form good habits and create a good body before either are reproduced.