Something along the lines of “OMG her biological clock will kick in and she’ll want babies and SUE US!!!” I suspect.
This, more or less. But I had already decided that even if I wanted kids, I was never going to want my own biological ones. My biological mother and father both didn’t want me and basically threw me away like yesterday’s garbage. They both take/took care of all of their other kids, though.
If I ever wanted kids, I would foster or even adopt somebody else’s unwanted daughter, try to pass it forwards. So they didn’t need to worry…
and she did only say it the once, and it wasn’t even to me (just in my earshot).