If you want to make parents anxious, lock them in a room with their thirteen-year-old child, and tell them they must talk to their teenager about sex. It's an issue that few parents feel comfortable and ready to discuss. And yet most parents know that they should, because of the importance of sex and intimacy in adult relationships, and because of the sexually charged environment we all live in. If kids don't hear about sex from their parents, they are going to hear about it from somebody else.

What are young adolescents going through? Below, two adolescent health experts explore this question.

Many parents don't think that children ten to thirteen years old are sexual beings yet. Are they?

DAVID BELL, MD: We are all sexual beings. Our kids are learning from us about good touch and loving relationships from almost day one. There are many exploratory behaviors that happen early in children. Parents need to be comfortable talking about sexuality with their children early on, and info adolescence.

JENNIFER JOHNSON, MD: I completely agree with Dr. Bell that sexuality is part of every human being's life, whether we're conscious of it or not, and that does include young children. But I think when kids are actually approaching puberty or have already reached it, they need some concrete information about what's happening to their bodies and what's going to happen.

Cognitively, I don't think that seven or eight-year-olds are ready to handle that information yet. It's just too hard for them to understand.

DAVID BELL, MD: I don't disagree with you. I think it's a developmentally appropriate conversation, and that as the child grows older, your way of talking with that child changes.

What are the markings of puberty?

DAVID BELL, MD: Some of the first changes for females are breast development, and one of the first changes is breast bud development. One of the later changes that people notice and appreciate more is the start of their first menstrual cycle.

For guys, it's sometimes a lot less noticeable, since the first change is growth in testicular size, and then, much later on, hair and muscle development. The growth spurt happens much later for males.

And there's a great degree of variation?

JENNIFER JOHNSON, MD: Yes, there is. In fact, for girls, the first sign-the development of breast buds-can occur as early as eight-years-old. It can also occur at age twelve or thirteen.

There is a big difference in the age of onset of puberty for both boys and girls. But what's interesting is that once that process is started, it's a relatively consistent period of time from the beginning of puberty until its completion.

When do teenagers begin to have sexual feelings?

JENNIFER JOHNSON, MD: Puberty is the result of sex hormones developed by the body, and these hormones affect the development of organs like the breasts or the penis.

Those hormones are also acting on the brain and causing the beginnings of sexual desires that the child will not have experienced earlier, at least not in that same way.

We don't really understand completely what triggers sexual feelings and behaviors, and how the hormones work, but definitely once the hormones are on board, then the desire is increasing.

At what age is masturbation fairly common?

DAVID BELL, MD: For males, age ten to thirteen.

JENNIFER JOHNSON, MD: Girls probably don't really begin experimenting with masturbation until they're more towards middle adolescence. I think that early adolescents are just kind of overwhelmed with what's happening to their bodies.

They're also making big transitions in their lives, going to a new, big school and being expected to perform very adult things cognitively and in their social world. I think they're just sitting there saying, "Okay, what's coming today?"

DAVID BELL, MD: Psychologically, they aren't quite there in early adolescence to experiment with sexuality. They may talk about it more. I know that, for females, since they are developing faster or at an earlier time, their desires are there, they're talking more about boys. And at that same period, boys are not talking about girls, usually. They're waiting.