Having studied French, I'm aware of the subtle social intricacies of the formal vs. informal "you." I figured Chinese was at least similar, i.e., informal for people of your generation, people you know well, your parents, etc.; formal for people you don't know yet or don't know well, in a formal situation such as a gala dinner, older people, etc.
I was reading a dialogue today in which a girl said, “妈妈好。您好吗？” I was stunned; I had assumed one would definitely use 你 with their parents.
Do you always say 您 to your parents, or was this a girl with particularly strict parents? Is it a cultural thing?
In your answer, please feel free to also go into the particulars of 您 vs 你, though I'm sure they're complex and subtle. A rough overview might give context.