White people keep asking me if my child is my own. How can I best respond?

‘Ultimately, you can only act in accordance with what feels right,’ writes Sisonke Msimang. Composite: ediebloom/Guardian Design

Dear Ms Understanding,

I’m Asian and my partner is white. We have a 13-month-old together and sometimes at the park I get asked by white mothers, ‘whose child am I looking after?’. It doesn’t happen every week but enough that I’ve been upset by it and would like to know how to respond. These are women I will probably see regularly and I don’t want to get into a situation where they get defensive or, worse, make a big deal out of apologising. Both of those reactions I find exhausting. But I do want them to know how inappropriate it is to assume I’m a nanny to my own child and ensure they don’t do it to someone else! What can I say?