"One might think so, but it's not always the case, I find," Mary says.

"I know the rules at home. When you grow up with the rules and know them so well, it's harder to misstep."

Which is not to say that she doesn't sometimes. Knowing the rules does not equal perfection in following them.

"Milliways is not as bound by rules, but that can make the boundaries harder to see. And I have to take care that habits formed here don't carry over too much at home."