I have 3 sons 11, 4,2 - I circ'd my oldest son because I was unaware of any other way. I am at peace with that. For DS 2, I was adamant I did not want to circ but DH felt the opposite. Like your hiusband, he wanted ds2 to look like himself and ds1. Although I knew it was wrong, I finally agreed to circ to make peace and have always felt sick about that. There is a difference when you are ignorant vs intentionally allowing your child to be hurt. For ds3, I was ready for a batte with dh that I was not going to back down from no matter what. Instead, he immediately agreed to not circ-ing when I brought it up. He had met more people who werent circ-ing and realized it wasnt neccessary. Which made me realize had I stood my ground with DS2, he would have eventually been ok with it.
DS1 is much older and I explained to him what circ was and that it was wrong and that when he was born I didnt know any better. He accepted that, no hard feeings. I think its a lesson in being flexible to change in life and learning from the past. DS2 who is constantly naked with DS3- whether it be bathing, running around my house naked all day, etc has never noticed a difference. Maybe he thinks its just different than his, just like Daddys and DS1's are different than his. So not an issue in this house.