We can argue till the cows come home what makes adults obese. However, along with that argument you have to factor in what makes babies and toddlers obese. They don't bicker about fat or carbohydrate or adopt a particular prejudice for they don't make lifestyle choices and have no choice what goes down their necks.
So, if you have an obese baby or toddler you have to answer the question - what did YOU do to make them fat? And why were obese babies 40 years ago the exception rather than the norm it is rapidly becoming?