Was she right or is there a reason she isn't teaching Sex Edication?

[°o.OT.a.m.a.r.aO.o°]

Hi everybody,
Now my question is a little wierd and personal but I would love some great advice. OK, the other day I was talking to my teacher. We were just having a random conversation and I told her that my grandma had my mom when she was sixteen and my mom had me when she was twenty-one. I was telling her that I didn't want kids until I am twenty-six and up. She said that because the generations in front of me (grandma, mom) had kids so young that I would too. Well, I'm only 14 and I am not sexual active. I know my fair share, and I didn't really believe her. But that's not all...I told her that I wanted to have 5 children, 3 girls and 2 boys. Well, since my grandma and my mom both had a daughter, then a son and then another son that I will too. I thought it was up to the sperm, and that it was 50/50 everytime. I don't know, but this has really been bothering me for the last little while.

Is she right, or is there a reason she isn't teaching Sex Edication?