It's never too early to start talking to your children about sexual matters. Openness, even with young children, will show that sex is an acceptable topic of conversation. Teach your child that you are available to discuss sexual issues, and establish a comfort level — for both of you — with the topic.

Here are some things to consider when preparing to talk to your child about sexuality. Don't feel like you have to include everything in one big discussion. Instead, talk about questions and behaviors as they come up.

It's normal for a child to explore his or her body and to do what feels good. Self-stimulation is one way a child's natural sexual curiosity is manifested. Boys typically pull at their penis, and girls rub their external genitalia.

Occasional masturbation is harmless. Children stimulate themselves to get pleasure, to relieve boredom or to deal with stress. A parent's overreaction can be harmful, because it may send the message that sex is dirty, shameful or frightening. Instead of expressing anger or embarrassment, explain to your child that it's all right to masturbate privately. If your child suddenly starts masturbating in the middle of a playgroup, try to distract him or her. If that fails, take your child aside for a reminder about the importance of privacy.

Many preschoolers are curious about others' bodies. Young children may want to touch their parents' genitals. They often try to satisfy their curiosity by exploring siblings' and playmates' bodies in games of playing doctor.

Such situations are normal. Avoid showing shock or anger. Explain that just as others shouldn't be sexually touching them, they shouldn't be sexually touching others. Stress that it's OK for children to touch themselves in private, but it's not OK for others, even friends, to touch them that way except in special circumstances, such as a doctor's examination. Point out that this is true for adults as well as for children.

"When your child is preschool-age, you probably won't be giving him or her lectures about sex," says Patricia Simmons, M.D., a pediatrician at Mayo Clinic, Rochester, Minn. "But sex education should still start early, through your responses to his or her questions and behaviors. You may not always know the answer or feel comfortable with the issue raised, but let your child know you welcome his or her questions, that you are a resource for sexual matters, and that if you don't have the answer now, you will help get it. Your child's physician may be a good resource or point you to useful references."

During the elementary-school years, most children continue to play occasionally with their own sex organs, as they did in infancy and the preschool years. Masturbation generally shouldn't be a cause for concern.

The first signs of puberty usually occur in the later stages of the school-age years. That presents a good opportunity to educate your child about sexual development, if you haven't already done so. Talk openly to your child about the physical and emotional changes that happen during puberty. Encourage your child to embrace these changes, not to dread them.

Don't worry if your child starts puberty a little earlier or later than his or her peers do. Children reach sexual maturity at different ages, and rarely does early or late puberty signal a medical problem. Be sensitive, though, if your child feels awkward and self-conscious because of developing earlier than most of his or her classmates. It may help to stress that every child is traveling along the same road toward adulthood and that everyone takes a different amount of time to arrive.

The American Academy of Pediatrics recommends that before they reach puberty, children should have a basic understanding of:

• The names and functions of male and female sex organs
• What happens during puberty and what the physical changes of puberty mean — movement into young womanhood or young manhood
• The nature and purpose of the menstrual cycle
• What sexual intercourse is and how females become pregnant
• How to prevent pregnancy
• Same-sex relationships
• Masturbation
• Activities that spread sexually transmitted diseases (STDs), in particular AIDS
• Your expectations and values

While your child is growing up, make an effort to gear your advice on sexual matters to your child's current phase of intellectual, psychosocial and moral development. The younger your child, the simpler the advice.