DP is circumcised but if BB#2 is a boy he won't be done. For all of the reasons already stated but I also don't think looking like dad is valid enough.

DD has breasts but they don't look like mine, her woohoo also doesn't look like mine (fortunately on both counts as she is only 2!) but she is quite accepting that mummy and she both have breasts and 'ginas, they just happen to look different. I can't see why a little boy would be less accepting seeing that a little boy and a man still look different down there regardless.

Also longer term most boys these days don't get circumcised so when a boy becomes a teenager he is more likely to look like his mates if uncircumcised.