Conversation held after a visit with the Pediatrician

Me: MM? That vaccine I said we were going to wait a few years to get? The one you can get anytime between the ages of 9 and 26?
MM: Yeah?
Me: That vaccine is to prevent a disease that causes cancer. In girls.
MM: So why do I need the vaccine?
Me: Because boys can carry the disease and give it to girls.
MM: How?
Me: By having sex with them. You'll get the vaccine in a few years, but there's no need for you to get it today, because you're not near the time when you'll be having sex with anyone.
MM: That's for sure!
Me: Now, you know that I think you won't be old enough to have sex until you're out of college, but just in case, we're going to get you vaccinated when you're 11 or 12.
MM: High Schoolers are old enough to have sex.
Me: Well...I disagree [thinking, please don't ask me when I started having sex]. Do you think high schoolers are old enough to be parents?
MM: No!
Me: 'Cause you know that a boy and a girl having sex with each other is how babies are made. We've talked about that. And every time a boy and a girl has sex with each other, there's a chance that they could be making a baby. So, if you're not ready to be a daddy, you shouldn't be having sex with a girl.
MM: Can boys make babies together or girls make babies together?
Me: No. They can't. But whether or not you have sex with a girl or a boy, it's best to wait until you are really grown-up and ready for all the grown-up stuff that happens when you have sex no matter who you are having sex with. And I don't mean like, you have a driver's license. I mean that you're ready to be making important decisions and taking care of other people and the stuff really responsible adults do, okay?
MM: Okay.
Me: And what do I always say after conversations about sex?
MM: Don't talk about sex with my friends.
Me: Right. Because their parents will want to talk to them about sex in their own time and in their own way. Okay?
MM: Okay!