Sure, it's an old joke, but maybe there really is something in the water in Chelsea after all.
Six sets of twins in the second grade, followed by five in first grade and another three in kindergarten, add up to 14 sets of twins at one school North Creek Elementary in Chelsea.
You could fill an entire classroom with just twins.
And it doesn't stop there. More are in the preschool program waiting to move up, according to North Creek Principal Marcus Kaemming, and a seventh pair was set to go into second grade but the family moved away last year, and still others are in the third and fourth grade as well.
Because twins occur in about 3 percent of all births among the general population, the magnitude of multiples at one school represents a significant statistical anomaly.
"It just seems like there's a lot of twins in Chelsea," said Kaemming, adding that to have so many pairs of twins at so many grade levels is "remarkable."
"In 10 years of teaching in the classroom, I can remember having maybe two sets of twins the entire time," he said.
If you think having twins is a challenge for parents, just imagine what it's like for the kids: to be followed around by your mirror image all day, and to be praised or blamed for something the other one did.
One second-grade twin, Raymond Apostoleris, was asked if he liked having his brother Marcus around constantly, at home and at school.
"I don't like it; he bugs me," was his honest-as-a-second-grader response.
Kristen McFate, mother of Will and Joe, the second grade's other male twins, said her sons show a little of that but deep down are very close.
"They are best friends," she said. "They're very competitive, but they will stick up for each other to the end."
Any parent can tell you that boys and girls of that age are at different levels emotionally, and the second-grade girl twins took a much more introspective approach.
"Playing with her is the best," Madison Adkins said about her twin, Hannah.
Quite the opposite of the Apostoleris brothers, Phoebe Kahler said she would not want to be separated from her sister Hannah.
"That would be a big problem," she said. "I would want to go to her school."
Cyndi Apostoleris, mother of Marcus and Raymond, gets to keep an eye on her boys during the day as a volunteer in the lunchroom and as a recess monitor.
"It's really exciting," Apostoleris said. "It didn't run in my family, but my mother always told me I would have twins, they were born a year after she passed away."
Kristen McFate, mother of Will and Joe, said she and the other parents of twins found out something extraordinary was going on when their kids first got together in a classroom setting.
"In kindergarten we started realizing there was more than one set," she said.
"I think it's neat for the kids they probably don't realize yet how unique it is."
Jamie Adkins, mother of Hannah and Madison, said the extent of the twin population became clear in first grade.
"I think somebody had mentioned something in kindergarten, and we started counting them last year," Adkins said.
"There were six and seven sets of twins in Mrs. Glover's first-grade class."
Although it's not at all unusual to see twins dressed alike, that's not necessarily prescribed in the parenting manual.
"Yes, they're twins but they are individuals," said Adkins, who dressed her daughters alike at first but now encourages that individuality even going so far as to place them in separate classrooms.
"They share a lot of the same friends but since they were in different classrooms they do have some separate friends," Adkins said.
"When one got invited to a party that the other didn't, we sat them both down and talked about that.
"I've tried to impress upon other parents that they're not a package deal," she added.
"If they want to invite one over and not the other, that's really OK."
And it is within North Creek's particular age group, 5 to 8, that individual character traits and personalities begin to express themselves.
"They are their own individuals; it's been neat to watch," Kaemming said.
According to Apostoleris, "It's fun talking about their different personalities; I've got yin and yang in those two."
Adkins saw it as just one of the demands of raising twins
"Developing separate friends has been the most unique challenge around this age, but that's one of the challenges that having multiples brings," she said.
While it is natural that parents would get together and share child-rearing stories with and seek advice from each other, the rarity of twins becomes its own topic of discussion.
"We see each other at school events, and you swap stories with the other parents (of twins), " McFate said.
"I probably shared more experiences and stories and looked for advice when they were younger," Adkins said.
"Now another close friend has twin girls, and the kinds of things we discuss are more educational questions and ideas."
With all those carbon copies of kids running around his school, does Kaemming ever get them mixed up?
"I do all the time," he said.