I wondered about this from the start, but in the end the answer was easy. Obviously a newborn is oblivious, but where's the dividing line? I just naturally go off by myself to dress and undress, because it's the privacy I'm used to. Around age three, he started copying my modesty.

I suspect it's the same for all parents and children, if you watch what you do and how they copy you. When they start imitating whatever your modesty calls for, just go with the flow and keep doing modest things. They will follow suit.