Obesity: genetics vs. environment?

I can’t believe researchers are still arguing about whether obesity is due to genetics or environment when it is so obvious that both are involved.  The latest study compared identical with non-identical twins and concludes that genetics explains an astounding 77% of the difference in obesity.  That percentage is enormous in biological terms and reason enough for skepticism.  The accompanying editorial gives additional reasons.  My take on this: of course genetics matters, but 25 years ago kids didn’t used to be so fat and rates of childhood diabetes (type 2) used to be much lower.  Genetics cannot have changed much in the last 25 years.  If the percentage attributable to genetics really is this high, it means that 77% of the population is susceptible to becoming obese if the environmental conditions so predispose, which they most certainly do these days.  Your take?