Saying the Dudley Dursley was a large child would be a rather kind way of putting it, he was definitely his fathers son that was for sure, with the same lack of neck and the same bright red face when they were angry. Dudley was also not the smartest child his ages, in fact he was often described by his teachers as a slow boy who often needed help in classes however his teachers didn't mind as he used to be a sweet child and they could forgive the lack of intelligence, but over time he had become quite rude and entitled, now this might have nothing to do with the fact he mother would always give him everything he asked for and it might be completely unrelated to the fact his father wanted Dudley to grow up just like he did meaning he was slowly becoming a more spoilt version of Vernon, but it was definitely related to those two things.