Of course not, it's just an observation that could lead to some correlation, or not. There are many environmental variables that alone or in combinations might lead to something but I doubt any grant money is available for such a non-pc study.
During my childhood every kid I knew was exposed to second hand smoke on a daily basis because you could smoke everywhere, including the Doctors office then. I didn't know one kid with asthma and very few with allergies. There also were very few obese kids but that's probably partially due to the more sedentary habits of our society.
Hey, they’ve concluded now that too clean an environment can lead to allergies and suppress kids’ immune systems, so who’s to say doctors won’t be purposefully blowing smoke in kids faces in a few years!?!