My XH was done, in a traditional Muslim way at age 8, and both my sons from that marriage aren't circ'd. They never asked why they were different, and now that they're old enough to understand (13 and 16) they know why their dad was done, and understand why I didn't get them done. I was prepared, if it was an issue that was raised, to explain my reasons for not having them cricumcised, and that's certainly not a difficult conversation to have, but it just never came up ever.