In my case at least, we only got soft drinks on special occasions, such as birthdays, Christmas and one or two other days of the year.
We all had/still have a sweet tooth, so there were usually biscuits or cake in the afternoon for a snack. However, main meals were healthier, contained vegetables and a little meat, washed down with water. We apso cycled to school (approx. 1.5km), played football ever second we got, went for walks with our dogs and we were generally more active doing housework, helping the auld man on the farm or ma in the garden.
The food they consume today is only a part of the issue. Soft drinks, super sweet "fruit juices", sweet shakes, etc. daily isn't good for anybody, but coupled with a sedentary lifestyle, they've got to be a killer.
In addition to this, I think the modern lifestyle, where BOTH parents HAVE to work to make ends meet, is the biggest issue. They simply don't have the time to keep this stuff in check. I see this at our home. Both the missus and I are on the go non-stop from early dawn til late at night. It's difficult to raise children right these days.