From the article:

Every August, for more than half a century, siblings who first met in utero take over Twinsburg for the Twins Days Festival, the world’s largest annual gathering of twins and multiples.

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The celebrants arrive in twos, threes and fours, mirror images of each other or as dissimilar as Mutt and Jeff. Many are first-timers, but even more are repeat attendees stretching back years.

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The festival is held the first full weekend in August and always in Twinsburg, about 25 miles southeast of Cleveland. In 1819, identical twins Moses and Aaron Wilcox changed the name of the settlement from Millsville, which honored a popular mechanism from that era, to Twinsburg, which celebrated a biological phenomenon now affecting about 3 percent of the U.S. population.

The community first hosted an abbreviated version of the event in 1976 as part of a larger U.S. bicentennial celebration. Three dozen sets of twins showed up. Over the years, the festival has ballooned. It now stretches over three packed days, and the number of twins and multiples regularly exceeds 2,000 registered sets. (By Sunday afternoon, this year’s tally was 2,085; festival organizers will release a final count next month.) The identical and fraternal pairings arrive by car, plane, foot and baby stroller. A handful cross rivers, oceans and the international dateline.

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The Double Take Parade is one of the festival’s marquee events, a 1.3-mile-long processional that, depending on the theme, can feel like a march of pop culture clones.

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The twins and multiples who attend Twins Days every year say the festival is a place where they can feel normal and understood. Where they don’t have to explain the difference between identical and fraternal or A and B (first and second born). Where they can wear whatever they want, which for many means dressing exactly the same.

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The festival dedicates a corner to research. This year, three universities, one plastic surgeon and Olay set up studies, taking advantage of the large sample size of twins — a windfall for researchers. Olay is studying how skin ages when genetics are not a factor.

For 20 years, the Procter and Gamble brand has conducted facial imaging on about 100 sets of volunteers, in exchange for a swag bag of lotions, serums and sunscreen.