I'm wondering too, how many of these kids end up fat after being stuck with these financial responsibilities. Stress is a major contributor to gaining weight. My parents, I think, did a pretty good job of balancing that desire to help me out and forcing me to carry some of my own weight financially. I did buy my own car, and I paid for my own apartment during college, and I shouldered the majority of my student loans, but Mom and Dad were always there to help me out and preemptively pay for things. The stress of working 20 hrs/week and going to school full time was enough to send my BMI well over 25 by the time I was 24.
Now, I'm not saying that this article's claim has no validity, but it seems that they aren't presenting all possible angles.