Well R., I hope you are still reading because I disagree with many of the people that responded to your question. I do agree that your issue is about boundaries not sex education but I also have a huge problem with some of the advice regarding sex education. I have never had the walking in problem because we always had sex after the tots were in bed and once they were in bed, which sometimes took about a gazillion years each night, a tornado could blow through the house and all three would sleep through it. If they were ever up when the door was closed, they had enough sense to leave it shut. I digress.
At 10, your son should be getting sex education at school, it is standard practice for the 4th grade in most schools not only in Texas but across the country. What people fail to recognize is that giving someone information does not give them permission to do things they are too young to be doing but does protect them from mistakes they are too clueless to understand.
Case in point. I met a woman through work years ago when she was probably around 23, she got pregnant at 15, why? Because she had no idea where babies came from and when her mother commented when she saw the boyfriend kissing her, she was already actually pregnant with her first child because she had no idea what she was doing when she first had sex.
I started having talks with my daughter about alcohol, drugs and sex when she was around 8. Alcoholics on both sides of the family so I figured I had better lay the groundwork for teen drinking early. As questions came up, our talks expanded and as we had many of them in the van, my sons have heard everything I have told her. She knows how I feel about sex morally, what our church's views are, and I have stressed that whatever decision she makes about having sex because in the end no matter what we teach them it is their decision, that I want her to make sure she is having sex for the right reasons, i.e. she loves the person, she is not doing it to make him happy when she doesn't really want to, she is not doing it because he is telling her that he will leave her if she doesn't, or out of fear that he will leave her if she doesn't even if he is not overtly pressuring her. For my boys, I tell them that I expect them to make sure again they love the person, that the woman really wants to and not just to make them happy or to keep them around.
My kids are 9, 13, and 16, they have so far, keeping finger's crossed, never walked in on me in a compromising position and while my 16-year-old has fairly good knowledge, I suspect that my 13-year-old thinks he knows more than he does and the 9-year-old is pretty much clueless at the giggly stage. They all know the mechanics and my youngest will get that portion of things this year in health class.
The reason I felt the need to speak up were the comments about keeping the 12-year-old innocent, which of course we all want to do, but not giving them any information even if they don't ask at that age is not necessarily the best thing to do. When my daughter was vaccinated for HPV, my OB/GYN said that they like to give the shots by 12 or 13 because they are useless once a girl is sexually active and way too many are by that age. Girls are getting pregnant in middle school and I suspect it is due more to lack of knowledge than anything else.
Kids on farms back in the day obviously had a great deal of knowledge about reproduction and yet they were not sexually promiscuous because they adhered to their parent's morals. It is no different today, whether you give a child knowledge because you took them to one of the state parks and they saw first large tortoises coupling and then I think it was the donkeys, or you teach them from a book, it is knowledge that they need so that they don't wind up in a situation they are totally unprepared to handle.
My talks with my daughter have progressed to exactly what she should do if she winds up on a date with a groping boy. If he doesn't listen she is to get out of the vehicle even if it requires physically disabling said boy, and call someone to pick her up. Too many girls get trapped into doing things they don't really want to do because it is so important for a teenager how they appear to others. I don't want my daughter hesitating because she is going to worry she might look stupid and please God forbid, wind up date raped.
For people that think you should overly limit the information you provide your children, my daughter currently plans to wait until she is finished with grad school to get married and to wait until she is married to have sex, so the information I always freely provided obviously did not give her permission to leave her childhood behind or lose her moral compass.