Are genes or the environment the main cause of obesity? (Problem with gene theory is that widespread genetic changes take more than just decades)

http://mtbeurope.info/news/2012/1210002.htm

Are genes or the environment the main cause of obesity?

3 October 2012

"He points to the recent fall in the cost of energy dense foods, alongside successful promotion by the food industry, and a decline in physical activity due to changes in transport, technology, and the built environment as key drivers for the obesity epidemic.

It will be important to identify genetic causes for rare cases that may be treated, he says. However, changes to the food and physical environment are going to be essential if we are to have a meaningful impact on the obesity epidemic."