This is VERY common. We went through it with my now 13 year old son and even sought professional advice. This is contrary to the other poster, but I think your pediatrician is right and we were also advised to just back off. If you push them or punish them he might start holding and then he will get constipated, even if he isn't now. Our son wore underwear and would ask us for a pull up when he had to poop. We gave it to him, he did his business, we quietly cleaned him up and put him back in his underwear. We were strongly told to not make a big deal out of it or to get upset. Like your family, it bothered my husband more than it bothered me. We kept up positive reenforcement in the meantime about pooping on the potty, read books and even talked about the wastewater treatment plant and what happens after we flush! A few months of this and he was pooping in the potty. I am still in touch with the director of his preschool at the time, and 10 years later she still talks about the day he explained the workings of the wastewater treatment plant to his preschool teacher! A new engine for his Thomas the train set helped too. Good luck.