I’m an only child. But I was rarely a lonely child.

My folks would drive half an hour each way to shuttle my school chums to and from our house so I’d have someone to goof around with on weekends. I always thought their jaunts were generous, but now that I’m a parent I realize it was for their benefit as much as mine: An hour of driving is well worth four hours of not having to help me inventory my Hello Kitty pencils and choreograph a dance routine to an entire Go-Go’s album.

When friends weren’t around, I played jacks or skated around the block solo. I dressed Barbie, undressed her and dressed her again, maybe with a winter muff this time. I sat alone in my room transcribing lyrics from my Walkman or playing solitaire. (It sounds sadder than it was.)

I remember once playing Twister by myself. I set up the colorful plastic mat in the living room, where my mother was trying desperately to lose herself in a novel, and I asked if she would mind simply kicking the spinner with her foot as she read, so that I might know where next to plop my left hand, or right foot.

Okay, maybe that one was a little sad.

But if being an only child taught me how to amuse myself and converse with grown-ups, it didn’t prepare me for the skull-rattling cacophony of sibling spats.

What is that?

My boys are playing quietly together, building something, sharing in a make-believe world so rich that I wonder how I ever managed to live without a sister — or how my parents ever got anything done without a built-in playmate to help me wile away the afternoons.

And then it happens. The cuteness and convenience of my kids’ desire to play together is shattered by the shrieks, sobs, and shoves that ensue when one of them touches the other one’s Lego propeller. Or looks like he might touch it. Or thinks about possibly, just maybe touching it.

I’m woefully ill equipped to handle such a row and find myself saying inane things to my bickering boys:

“Who got it out? Who called it first? Who had it last?”

“Okay, so you bought it with your own money. Well…then…can he pay you to play with it?”

“No one touches anyone’s stuff anymore! Nothing! Ever!”

My husband, who has a younger brother, laughs at me.

“I’m tired of being sucked into these ridiculous squabbles,” I moan. “I don’t want all this arguing, all this noise.”

“Then you shouldn’t have had two kids,” he says, still snickering.

I didn’t set out to have two kids. I figured one was plenty. I never felt slighted for not having a sib, and I like how one-child families get to be more adult-oriented, toting Junior along on classy wine-tasting vacations rather than cramming a whole bratty brood into a Disney-adjacent motel room and calling it “fun.”

But I became so enchanted with our first child — so impressed with our ability to produce a fully functioning human being — that it seemed a flagrant waste of our talents and biology not to make another.

And when the boys aren’t locking horns over Legos or battling over the last brownie on the plate, I’m glad we did. Because here’s something else I never realized about siblings: Their bond will be the longest relationship they’ll have in their lifetimes. Even after their dad and I have gone to that wine-tasting vacay in the sky, our boys will be there to comfort and cheer one another. To flick the Twister spinner. To offer simple company and call it “fun.”

Assuming they don’t maim each other first.