Now that Barbie’s creator has died, a lot has been written about the doll’s impact, with a billion sold since 1959.

But I wanted a more specific picture, so I called the most seasoned Barbie expert I know.

My brother, Douglas.

He is a businessman who spent most of his adulthood snowboarding, rock climbing and chasing women.

Then something happened that altered his life.

No, not getting married. That was minor.

It’s what happened after he got married.

He and his wife had three girls.

Douglas is now 46 with daughters aged 4, 2 and 8 months.

Were you to ask him the primary “brand” or “theme” in his home, it’s not even a contest.

“Barbies,” he says.

His daughters have Barbie pillow cases, Barbie nightgowns, Barbie coloring books and Barbie T-shirts. They have Barbie plates, Barbie forks, Barbie spoons and Barbie cups.

“When I’m not drinking out of the pitcher,” he told me, “I’ll sometimes grab a Barbie cup without thinking, just because it’s the closest thing, and use it.”

His descent into this world was unexpected, as we both have childhood memories of leaving the den when a Barbie commercial came on, because you were a girlie-man if you allowed yourself to listen to it.

There were five sons in my family no daughters and we were so against dolls we wouldn’t even play with a GI Joe as we felt it was a doll in disguise.

When Douglas had his first daughter, Lila, he assumed things would still go his way. “I thought we’d play with Army soldiers and throw around a baseball,” he recalled.

Lila got into Barbies instead.

At first, Douglas tried to limit his investment. He told his wife “One (expletive deleted) Barbie will do.”

I asked him if he was successful.

“Not at all,” he said. “Barbies are like kudzu. They’re like the Blob. They take over.”

They now have more than 20 Barbies in the house.

During his pre-daughter days, he was constantly buying gear for rock climbing and river rafting. “I used to think it was my job to keep adventure companies in business,” Douglas said.

That has shifted. Today, he figures he’s responsible for 10 percent of the Barbie brand’s quarterly revenues.

He was sure his second daughter would resist Barbies, since she is less of a girlie-girl, and would do such things as slug her older sister and then announce, “Not sorry.”

But she’s now into Barbies, too, and no matter how many Douglas buys, they still steal each other’s dolls and get into Barbie fights.

He presumes his 8-month-old will soon follow, which means Douglas will be playing with Barbies well into his 50s.

I asked if he really does help his daughters play with the things.

“It’s my life,” he said. He reads them Barbie bedtime books, watches Barbie movies with them, and for an hour at a time, plays a Barbie computer game where you dress up Barbie Cinderella in a gown, and look for her prince. Or maybe it’s Barbie Sleeping Beauty, he forgets which.

“Isn’t that better than reading potty-training books into your 50s?” I asked.

He told me he’ll be doing that too.

He added: “We even have Barbie birthday parties.” This involves not just a Barbie cake, Barbie gifts and Barbie theme but the appearance of a real-live Barbie.

“Usually,” Douglas said, “the dads don’t like to show up at birthday parties, but when I told them, ‘Hey, a live Barbie will be there,’ all of a sudden, the dads are all coming, on the presumption the live Barbie will be of the same proportion as the doll.”

I should add here that a scale analysis has shown that at 5 feet, 6 inches, Barbie’s measurements would be 39-21-33. That only occurs in one of every 100,000 females. Apparently, the woman who played Barbie at the party was not to scale.

“You can imagine the dads’ dismay,” Douglas reported, “when all they got was this squeaky-voiced, flat-chested, out-of-work actress pretending to be Barbie.”

He assumes there will be far fewer fathers at his future Barbie parties.

Does he have advice for other macho fathers who think they can resist?

“You’re powerless,” he said. “It’s like trying to keep toy guns out of a house full of boys. It’ll come in anyway through television, the computer, their friends. Barbie permeates the culture.”

So it may be true that with a billion sold, Barbies would be the second or third biggest nation on earth but if you really want to know the impact of Barbies, talk to my brother, Douglas.

Talk to him when he reaches age 50, with fading memories of rock climbing and river rafting.

And ask him how he spent his week.