Only Children Have Higher Risk Of Obesity

True and not true.

Children who do not have brothers and sisters have a 50% higher chance of being obese or overweight than children who have siblings.

Not true - it is not only children who are at higher risk. Overweight adults are, too.

True - parents probably are overfeeding their only children even more than parents who overfeed multi-child families, since there is no competition for Calories (and Calorie-purchased "love") in the family from other kids.