One personal question I did ask lesbian parents, who had lovely twin daughters from the artificial insemination of one of the partners, was whether they had concerns about future discrimination against the girls as they grew older and went to school where they lived. The kids were pre-schoolers at the time.
Of course the little twins were not around when I asked that. And the mothers answered quite frankly that they were indeed concerned, and they had to monitor that. But they added that the girls themselves were quite comfortable with the idea at the moment, considering both of the adults to be their mothers. They distinguished between the parents by calling one Mom and the other Mommie.
I guess I felt I could be that intrusive because one of them was the sister of my BF at the time, and we were staying with them a few days. I continued to see them all periodically over the next 2 years, even spent a Christmas with them and my BF's parents, until I eventually relocated. And the little girls really did thrive as they grew, very adorable, very heart-warming to see them so happy and doing their kids' things in the care of 2 loving parents.
Now that I've read the linked article I wonder if my own question was in fact out of line, too. It didn't seem so at the time, all very friendly as we sat in their house talking about the little girls and how wonderful they were. I guess even the most well-intentioned of us can mess up, I never thought about it before.