There are parenting milestones we all look forward to: the first step, the first school dance, the first wedding (which, you hope, is also the last wedding). And then there are the moments most parents dread, like when your son or daughter comes to you, eyes wide and filled with questions, and asks, “Mommy? Daddy? Where do babies come from?”

The good news: It will never happen. As any veteran of the War with the Birds and the Bees will tell you, children never come to parents like that, ready to listen and open to wise counsel. What will happen is your children bursting in when you’re tired or distracted or totally unprepared and crowing, “Mommy! Derek said that Emma said that one’a these days a baby’s gonna come outa her pee-hole!”

Thus it begins.

I weathered the first rounds with my own kids some years ago. Since then I’ve had training as a teacher and counselor in Our Whole Lives, a sex ed program created by the Unitarian Universalist Church that has guided thousands of children through some difficult years. Having led that program for almost a decade now, I’ve spent many hours with hundreds of middle and high school kids discussing the undiscussable. I’ve even taught other parents and teachers how to use its insights. So I can say with some confidence:

Give up your fear of the big talk

It’s a myth. Instead, be ready to seize a random opportunity to start a more involved and beneficial conversation about sex — one that, in the long run, will work out far better for everyone. Many of the parents who have lived to see their children grow into well-adjusted adults offer the same fragments of sage advice:

Get your facts straight

As your children enter the “curious” years, do a little homework of your own. Brush up on the basics of biology, of course, but also learn the latest about AIDS and other sexually transmitted diseases, and gather the facts on the latest birth control devices and methods. Be sure you can answer pretty much any question about sex you can imagine, because you’ll probably hear them all sooner or later.

Understand that kids think they already know everything about sex … and that they’re wrong, of course

Notice the example above didn’t end with “Is that true, dear mother/father? Please tell me.” Quite the contrary: Between the severely redacted sex ed classes most schools offer, the endless supply of half-truths found in everything from MTV to CSI: Miami, and good old-fashioned street-level misinformation from peers and siblings, your kids think they know all about sex and its consequences. They are not coming to you for education; they’ve got that covered. At best they’re coming to you for confirmation, and the most repeated phrase you’re likely to use is “Well, honey, that’s not quite true.” Which leads to:

Practice not being surprised, shocked, or offended

It’s guaranteed: You will be stunned by some of the crazy stuff your children actually believe, and it will be your job to sift through these horrible assertions to unearth a teachable moment. If you seem awkward or judgmental in your reaction — no matter how bizarre the assertion or terminology — they will either clam up entirely or reduce your credibility score to near zero. So …

Make it a conversation that lasts for years, not a lecture that lasts for hours

Most kids won’t sit still for a lengthy talk, and even if they tolerate it, they’ll retain nothing. Usually they want just a little information: Can you get syphilis from a doorknob? Do mosquitoes spread AIDS? Does drinking one glass of wine before you even know you’re pregnant mean your baby will have six fingers and a third eye? And if you answer the question they ask — and only the question they ask — then listen to answer the next question, all the while resisting the temptation to launch into a prepared speech, they will almost certainly come back to you for another talk, and soon. And most important: They’ll believe what you tell them and (secretly) respect your honesty.

Ultimately, what you want is not that one golden memory of the moment when you taught your little ones the facts of life. What you really want — what’s best for you and your children — is to open up an ongoing conversation that will last a lifetime. It won’t start the way you expect, and it will never really end, but it can become an important and cherished aspect of your relationship with your kids.