Summarize this article:

If you get an indication that your child is being exposed to sexual information, then it is time to start talking with them yourself. Even infants are curious about their bodies, and by preschool age they may show an intellectual curiosity regarding others' bodies as well as their own. By eight years old many kids are ready to have some form of a sex conversation with you. Remember to keep the conversation age appropriate, too. You don’t need to provide all of the biological details to a young child, but it is important to let them know you are there to talk. By middle school your teen will likely have had at least one brief sexual education discussion in class. This is a good age range to clarify any biological information or details that may be confusing. When your child reaches high school, you may want to focus your attention on safe sex, including STD prevention. It is best to discuss sex when you and your child are alone. This will allow both of you to be honest and straightforward without worrying about peer pressure or embarrassment. Many parents find that the car is a great place to talk. Or, you and your child could talk while taking a walk.  It is often helpful to talk about potentially uncomfortable subjects in the middle of completing a familiar activity. For example, you might want to initiate conversation in the middle of a basketball game, if you and your child regularly play together. Consider your family dynamic. Some children may be more comfortable having initial conversations with parents, guardians, or a close relative of the same biological sex. Be aware that your child has probably been exposed to a wide variety of sexual information fairly early on. The internet, radio, and TV all express sexualized messages on a regular basis. You might start the conversation with your child by asking them what they’ve seen or heard.  For example, you might say, “You had the sex ed class in school today. Do you have any questions about what you learned? Did anything concern or confuse you?” To gauge what kind of sexual information your child is encountering, try flipping through their favorite magazines. Or, listen to their music. Consider your conversation with your child as one that is ongoing and continual. Look for opportunities in your daily life when you can bring up the subject or provide them with some useful information. Pop culture provides many such opportunities. If you both are watching a TV show that mentions a sexual myth, go ahead and correct it for your child. Normalizing the conversations can help your child better understand in the long run.  Also, be aware that you could overwhelm, or scare, your child if you try to lump everything that you want them to know into one talk. Instead, purposefully spread this information out over time, building a relationship built on trust and open communication.  Tell them that you're available whenever. For example, "If you think of more questions you have, feel free to ask me sometime."

Summary:
Start early. Choose the right place and time. Expect them to possess some prior knowledge. Talk about sex more than once.