I guess Aaron's not so big

Aaron had his 4 month check up yesterday and I was kind of surprised by how small he is. He only weighs 13.1 lbs and is 25 inches long. That puts him in the 10th percentile for weight and 50th for height. The doctor doesn't seem to worried about it, but I'm stressed trying to think about what I can do to help him gain weight. The girls are always small at their check ups so I guess I just have small children. I always figured I'd have these giants since everyone in my family is so big, but I suppose we'll just have to deal with our little bitty kids.