She'd known about the chemical.. The cause of his blue appearance in her own world. She just hadn't been thinking of it, since he looked so different here.
"I see," she said. She felt her face flush, and she wasn't sure what she was feeling, precisely. It was pragmatic of him, she supposed, to be thinking of that. Part of her wanted to encourage him to hurry up and figure out, and part of her was afraid that it would turn out the chemical had created a hereditary change, and Hank would be unwilling to have kids.
Obviously, they weren't going to have a child anytime soon, but what if his research took years? What if they didn't find out the worst news until Anya was in love with him? She didn't want to go through with Hank what had happened to her and Warren. What if they didn't find out until she was too old? She was already in her thirties.