About a month ago I overheard Jesse and Nick as they played with dragon figurines in the living room. Nick’s little voice piped up. “We can’t get married yet because we haven’t fertilized yet.”

Eh? I peeked around the corner from the kitchen. The dragons were facing off. “I will fertilize you,” said Jesse’s dragon. “Fertilize fertilize fertilize.” Her dragon pecked Nick’s dragon in the mouth with each iteration.

Nick continued the play. “We need more babies! Shoot more fertilizer!”

I had to walk away.

I’ve wanted to have a straight-talking talk about sex for years, but something has always stopped me. I’m just not sure how to do it. This is not a conversation my parents ever had with me. I learned what sex is from my friend Robin in 6th grade, as we played on the playground swings after school.

That’s right. I was a child in the dinosaur days when, as an eleven-year-old, I could just stay after school to play before I walked home. Because no one was home. I would hang out, without any adult supervision, and play with Robin or anyone else who could stay after school. Then eventually I’d walk the half mile or so home, alone, and unlock the door and get myself a snack, alone. Sometimes a brother would come home, and my mom would come home from work a little before dinner time. It’s a miracle I survived.

What? Oh, sex. Right, so Robin told me about sex. It came out of the blue, and of course her communication had a prurient edge to it, the feel of a dirty secret — because my parents never, ever talked about it with me. I was stunned and grossed out. My mom never even talked with me about menstrual cycles or planned ahead for my first period. My grandma told me a bit about it, but it was all so confusing. I bled one day and thought I was dying. My mom nodded and handed me some sanitary pads. She didn’t even show me how to attach them to my undies.

At some point I swore to myself that I wouldn’t be the repressed parent. My kids would know what sexual intercourse is before they were three. Well, five. Maybe five. I’ve lost sleep about this. I’ve made plans, I’ve given it a lot of thought, I’ve considered different tactics and tried to settle on a course of action in introducing the topic.

Yet here I am with a nine-year-old and five-year-old, and until last week I hadn’t talked directly with them about sex yet.

In my own defense, Jesse has other issues we’ve been dealing with, and Nick is just suffering in ignorance in the wake of Jesse’s needs. I have taken jabs at some technical details. Jesse and Nick know babies come from fertilized eggs for most animals. They know each of them was made from a piece of mommy (egg) and a piece of daddy (sperm). Jesse even asked the key question recently (i.e., some time in the last year). “How does the piece of the daddy that becomes part of the baby get inside the mommy?”

Oh dear, I thought. But somehow, I still couldn’t bring myself to go the distance.

So I got a book recommendation, “IT’S SO AMAZING! A Book about Eggs, Sperm, Birth, Babies, and Families.” By Robie Harris and Michael Emberley. It took me months to get around to buying it, but I finally overcame whatever was stopping me.

This book is SO AMAZING. I don’t have to think about anything. I just have to read the words on the page, while sitting on the sofa with a child on either side of me.

It eases into the topic so smoothly. First it teaches anatomy — in cartoons with fun colors, but anatomically correct drawings. You see drawings of naked humans at all different ages, both genders. You learn about the parts of the body that are the same and different on boys and girls, the different parts that are on the inside and the outside. I discovered that drawings of the vulva make me uncomfortable. Not my thing. My mom never gave me a mirror and encouraged me to learn my body.

Jesse walked away without a word when we got to the page about male anatomy, but she came back the next day and asked to continue the book. Nick pored over the pictures with Jesse and then asked me, “Are there two kinds of penises? Which kind do I have?” We chatted about circumcision.

After several days of studying all the parts and staring at anatomical drawings and learning the names of things — ovary, fallopian tube, uterus, cervix, bladder, vagina, labia, clitoris, vulva, seminal vesicle, vas deferens, prostate gland, urethra, epididymis, scrotum, testicle, foreskin — the topic had become prosaic, clean, bored-sigh-inducing. Perfect.

Then we learned about the journey of the egg and the menstrual cycle, and then about the journey of the sperm out of the penis and erections, and then about the journey of the sperm through the female body.

Not once did the kids ask how the sperm gets there. I was amazed. I wasn’t sure how that final bit of news would go over.

This morning before school, Jesse wanted to read on, and we finally got to the pages describing sex. Nick wasn’t interested and wandered off to play with dinosaurs. The last piece of the puzzle was more like a little epilogue than a big bang. The sperm has to get inside the mom’s body, and the way in is the vagina, so there you go. The bodies get close, the penis ends up inside the vagina, and the race to the F-tubes begins.

“Really?” said Jesse. She wasn’t grossed out, freaked out, or zoned out. She was just curious. “That can happen?” We talked about it, not in much detail but just to get clear that, yes, the penis can go inside the vagina and that’s how the sperm gets on the right path in the hunt for an egg. We talked about love, intimacy. We talked about intra-family taboos.

And then it was time to go to school. It was like we had just learned how plants get cloned, or how hydrogen and oxygen combine to make water, or how 5 times 9 is 45.

All that worrying for no reason. All I had to do was buy this book. It has all the answers. I never have to worry about sex and my children again.