I have a 10-year-old son who is being homeschooled. He is in a Medieval, Reformation, and Renaissance unit and will be reading a version of The Canterbury Tales that has been translated into modern English by Barbara Cohen. In this book, specifically in "The Wife of Bath's Tale" there is a knight who rapes a maiden ("forces himself upon her despite all her efforts to stop him"). I'm not sure if I should explain what that means or if it would be better to read it as a read-aloud so I could just edit it as the knight "hurting" the maiden.
My son knows the biology involved with reproduction and that marriage is the only place for intimacy but does not have detailed knowledge about what "intimacy" means. What age should ideas like prostitution, rape, molestation, etc. be discussed? I know most are going to read this and think "when the child is mature enough for that information," but what clues do I look for to determine that? He is, I think, curious about words such as "harlot" or "seductress" that he has heard from Bible passages or come across in his own reading. He has asked me to define those words and my answers have been to say they are women who are not respecting the purity of marriage between a husband and wife. Or I will say it is a woman acting like a man's wife when she really isn't. Maybe those answers have been too watered down? In public school, we had the "talk" about our bodies changing in 4th grade. In 8th grade, we had the biology of reproduction and I also remember learning about what rape meant. Finally, in 10th grade we had the various contraception methods, homosexuality, masturbation, etc. taught in our health class. I do not intend to follow this schedule but mention it only as my "worldly" knowledge of when such topics are discussed. I fully expect your Christian answer to differ with that timeline.
My general answer for younger children is giving them only enough to satisfy their questions. The answers you have given are quite good and age-appropriate for your son.
When is a good time to give more details? That depends on the physical maturity of the child, which varies greatly. Basically you will want to discuss matters of sexual maturation sometime after puberty begins.
For boys, puberty generally occurs between 9 and 16. The first sign is a gradual enlargement of the testicles, which most boys don't notice. Second signs are genital hairs, which look like pimples at first and then very fine hair, or erections. Generally, by this time a boy needs some warning about what is coming up so he is not so worried about what is happening.
For girls, puberty generally occurs between 8 and 16. The first sign is either a growth spurt or menarche. Young girls need a warning about menarche in advance to avoid panic or embarrassment.
Both boys and girls generally put on weight just as puberty hits (the body is storing fat to prepare for growth); however, I have seen some children so skinny that their "fat" stage just makes them look more like a normal weight child. Similarly, it is hard to distinguish between overweight and a little extra overweight. You will also suddenly find your child extremely shy about his body when before he never gave a thought about you seeing him dressing. Finally, watch your child's feet. A sudden increase in shoe size is a good indication that puberty has already taken place.
Once a child nears or passes puberty, my rule is that I will answer any question that a child knows enough to express. It might be embarrassing for both of us, but if they are mature enough to think of the question, then they are mature enough to hear the answer.
As an example, one eleven-year-old boy was getting ready to do a Scripture reading that included this passage: "Even Levi, who receives tithes, paid tithes through Abraham, so to speak, for he was still in the loins of his father when Melchizedek met him" (Hebrews 7:9-10). I had asked if he knew all the words, and he asked me what "loins" meant. I told him that it was the pelvic reign. He was still confused, so I told him it was the area from the waist to the thighs. That just made it worse. "How can a son be in his father's loins? Babies come from mothers!" So I explained that the main part of the loins were the genitals and that when a man was old enough to have children, he would be able to produce sperm. A sperm from the father joining with the egg of the mother is what produces a baby. That satisfied him for the moment, but his mom told me later that that night he was full of questions about how a man's sperm gets into a woman. It caught her completely off-guard. I then told her of his earlier questions. Both mom and dad were too embarrassed to give the details his questions needed, so I had a short study with him over the mechanics of growing up. When he gets a bit older we'll talk about sex and his responsibilities to remain pure, but at the time his body had not matured to the point where he understood things like sexual feelings or how his body would respond to those feelings. If he doesn't ask first, I will bring the subject up when I notice he is beginning his growth spurt.
For an older teen, one who has gone through the bulk of his growth spurt, I try to make sure the parents or I sit down and talk about all the details about sex, except details on how sex is done. I make sure they are well informed about what sex is because many teens think only vaginal intercourse is sex. We talk about lust, pornography, and the dangers of trying to cut things too fine. We go over excuses teenagers use to justify having sex before marriage and why they don't justify it. It is also at this time that we talk about how people pervert sex: rape, prostitution, homosexuality, etc. All of these topics are covered even if the teenager doesn't think to ask a question concerning them. Our society is over-sexualized and a teenager caught off guard won't know how to respond if he hasn't thought out the problem in advance.
I had a fourteen-year-old boy in the congregation who needed to know about his sexual responsibilities. I arranged to study with him. It wasn't more than two weeks after we talked about the dangers of having sex outside of marriage and being aware that it wasn't always the boys who try to seduce the girls that he came to me and said: "You'll never guess what happened in school today!" A girl in his class came up to him and told him that she decided to lose her virginity and that she wanted him to be the one to do it to her that afternoon. The boy was so pleased that he knew exactly what to tell her: "no way!" Knowing he was flattered by her advance, I pointed out that if he asked some of the boys in his class he will probably find that she isn't a virgin and that he would not have been her first. He confirmed my guess the next time we met. Based on what his friends told him, at least five other boys had already had sex with her. That made a great lead-in to a discussion of sexually transmitted diseases.
Don't think that talks about sex can be put off until the child is college-age or even a junior or senior in high school. Surveys indicate that a lot of kids start playing around with sex as early as fifth or sixth grade -- if their bodies have begun to mature. Recent statistics indicate that two-thirds of all sexually transmitted diseases are occurring in people 25 years old or younger. One-fourth of all new sexually transmitted diseases occur in teenagers. Kids are having sex at alarming rates!
Put off discussions until a child is old enough to understand because his body has matured enough, but once he has matured, you cannot ignore the topic thinking his innocence will protect him. The world won't spare him just because he doesn't know any better.