Some say it could be something in the water. Others point to a tree with mystical significance for locals. Maybe it's just chance. But neighbours marvel at the 12 sets of twins living along two consecutive blocks in western Havana, ranging in age from newborns to senior citizens.
"We were the first ones," said Fe Fernandez, 65, who wears her gray hair closely cropped. "It's incredible!" said her identical sister, Esperanza, who shares the same features but whose black-dyed hair falls to shoulder length.
At first blush there isn't much about 68-A Street to mark it as different from anywhere else in the city. Children play ballgames in the road nearly free of traffic, as tropical music floats out from behind graceful porches and balustrades. But if you spend any time here, before long you might think you're seeing double.
"Hi, I'm Carla, and this is my sister Camila," said Carla Rodriguez, a smiley, bespectacled nine-year-old. "We're twins and we love living on this block because we have twin friends."
Tamara Velazquez, who's been busy raising six-year-old identical sisters Asley and Aslen, said: "I never expected it. No fertility treatments. It was my first pregnancy, and at five weeks they did an ultrasound and I was carrying twins.".
"It's a lot of work. It requires a lot of patience," Velazquez said. "They are very active and dominant, although each has a different character."
Ten of the twin sets here are identical, and the other two fraternal. None of the mothers interviewed said they had received fertility treatments, although most said multiple births run in their extended families including relatives living elsewhere. None of the families are related to each other.
All but one of the sets were born into these homes, and the lone newcomers moved into a house that was vacated by twins who moved to Spain. Others have died or moved away over the years. "Twins leave, twins come," Fe Fernandez joked.