What a wonderful question.
Most people would respond to a curious child would be:
Mommy and your daddy loved/love each other very much and we did a special act (sex) to have you. You grew in a special place in mommy's tummy called the womb. After 9 months of you growing, you came out of mommy and you were mine.
Let's be real it's not an easy talk. You have to explain all these questions from your child, who doesn't quite understand. And they are like well if Daddy loves you so much, where is he at? Or, what is a vagina?
In this day and age, simply, the stork story is not going to get you far. Then you have to explain why Jared from the playground said that mommy is a liar.
Then your kid is left with this weird image of what is really happening.
The sex answer is the most common answer.
It's not the answer I will get to give.
Depending on the route I take for having a child one day, I will have to explain accordingly.
I could take the approach of:
Mommy wanted you more than anything. She fell in love with donor 247 because he played football for Virginia Tech, he is a neurosurgeon, and he didn't bald or prematurely gray. The place you grew as a baby, or your greenhouse, was up to code. Mommy took a bunch of medicine and had a bunch of shots for weeks that made me very nauseous and cry because, I saw a photo of a baby Otter, and I thought it was cute.
You were made in a party plate, aka the petri-party palace with half of mommy's hormone injected eggs, and half of sexy donor 247's semen.
They partied 2-6 days strong.
They were like the Oprah of Eggs and the Vincent Van Gogh of Sperm.
Defying all odds.
You decided to pull residency to grow in the greenhouse for like 9 months, because it was allowing you to eat and stuff, but then, it got way too cramped and small. Plus, you were like really wanting to hang out with me, so you came out and now, we are best friends.
Or Something like that.
I'll write a book. I'll hire Eric Carle to be my illustrator. My book manager, Trevor, will have to do that research for me to make sure we are really depicting the need that suctions out the egg from the vaginal wall is given its due diligence. Subtle, yet graphic.
It's a work in progress, but I definitely feel I am on to something here.