The first time the question came up, you managed to distract your child ("Hey, look! Isn't that Dora the Explorer?"). But you're just delayng the inevitable. Not only will you have to answer your child's question eventually, you'll actually have to answer it several times as her development permits different levels of understanding. Try to keep your cheering down to a minimum.
Understand the question
The first step to answering the big question is to make sure you understand what your child is actually asking, says Dr. Susan Bartell, family psychologist and author of The Top 50 Questions Kids Ask (Sourcebooks, 2010). A young child may simply be asking if she was born in California, like her friend. If you respond to her initial question with something as simple as, "What made you think of that?" you can figure out where your child is coming from.
Asking a question or two before you provide answers also lets you see how much your child already knows. You might be surprised to discover what he's already learned from his friends or siblings -- and you'll have a chance to see how much of that information is less than accurate.
Use age-appropriate language
Once you've ascertained that your child is, indeed, asking about where babies really come from, it's time to answer. By first grade, your child is probably ready to hear that "when a mommy and daddy love each other very much they lay very close together and they make a baby.," says Dr. Bartell. "If you feel compelled to be very specific, say 'A mommy has a vagina and a daddy has a penis. The daddy puts his penis in the mommy's vagina and they can make a baby.' Expect your child to be shocked," she says, and adds that many children will express disgust.
It's not necessary to give your child's friends' parents a heads-up, says Dr. Bartell, but it is important to make sure your child understands that he should not share this information with anyone without your permission. "Be firm and strict about this," she cautions. And if, despite your warning, your child races off to tell his friends what he's learned, you should remind him of the rule and let him know you're unhappy. At that point, says Dr. Bartell, you need to "tell the other parent what your child has shared." Don't agonize over it -- this is somewhat inevitable, and it's the way most kids learn about sex, she says.
What not to say
Just as important as what you tell your child is what you don't say, says Dr. Bartell. Don't give blatantly fictitious answers involving storks, and don't tell kids that the baby grows in mommy's belly and leave it at that. "Your child may worry that he or she could spontaneously become pregnant. Explain that the baby grows in a special place … that only grown-up girls have," she says.
As you talk to your child, Dr. Bartell recommends asking lots of question to ensure understanding. "Go slowly, and stop when their curiosity has been satisfied," she says. "Don't tell them more than you have to" for their current stage of development. In fact, with first graders, there's no reason to use the word "sex" -- unless the child asks.
If your child is adopted, your explanation should involve that. Your child may be looking for extra reassurance that he belongs in your family. If you have a blended family, talk about that, too. Above all, kids want to know that they are wanted and loved, so be sure to tell them that they are -- as often as possible.
More tips on talking to kids about sex: