Thanks for opening up this conversation.
Tiresome, and inconvenient. But still a white experience for you. I know plenty of “brown” mothers of fairer skinned children who are (with great kindness) presumed to be the hired nanny. Even though your interlocutors come from the same place of ignorance and idiocy, the effect on the “brown” mothers is not just tiresome, it is demeaning and worse.
Then of course there is the gendered issue of why _fathers_ never get this kind of question. Men, of course, are allowed and assumed to transgress racial boundaries in their choice of mate/co-parent.
Finally, if this question is posed to you in the presence of your children (unbelievable, but adults say all sorts of moron things as if children can’t hear), perhaps the correct response is one of the following:
“From some woman’s womb, why, are you different?”
“From Earth. Where the f**k are you from?”