Last Names

I was quizzing Lou to see if she knew what my last name used to be. Here's our conversation:
Me:"What did my last name used to be?"
Lou:"I know that. It used to be Fleming."
Me:"Why did it change? Why do I have a new last name?"
Lou:"well, when you get married, the female changes her last name to the name of the male and the male keeps his last name."
Me:"You are very smart(as I run to the computer to quickly type this and point out that she didn't call us 'boy' and 'girl'...she called us 'male' and 'female' and I swear she doesn't sit around watching Nova and National Geographic all the time. I'm not even sure where she picks this stuff up! I certainly don't refer to women as 'female' around her. She is absolutely hilarious! If she stays on this path, I see a very, very intelligent woman (or should I say female) in our future.)