C.K.
Hi J.,
I'm a mom of 3 boys and 2 girl, plus I owned a preschool for many years. It is very common for boys to remain in diapers until they are around 3 1/2 and I wouldn't even get too excited about it is he were 4 years old. I had a 3 year old son, who had a very difficult time being potty trained. He wanted to go to preschool (during a time when I didn't own one). At that time preschools didn't take children who weren't potty trained. We were closing on the time he would begin preschool, but he wasn't potty trained. So, I decided to just turn the entire thing over to my husband. I asked him to take our son into the bathroom with him every time he had to use the toilet. It only took one week and my son was using the toilet on a regular basis and doing it right.
I now have a daughter, who when she was little wouldn't do anything until she could do it right. So, I understand that part. My thoughts are that maybe your son, would benefit from your husband taking him in with him to use the toilet, too. If your son had no obligation to use the toilet, he'd be able to see how it is done right for a male person. My guess is that your son witnessing the correct way for him, would spur him into action and add bonding with his father. When I did that week on male modeling, I completely took myself out of the picture. I no longer asked my 3 year old to watch me or his 17 month older brother use the toilet. We just had him go in with his father to watch with no pressure to actually use the toilet himself. It took the pressure off our son and suddenly we found him in there all by himself. I hope my experience will help you.