No one knows who, exactly, was the first kid to play "The Floor Is Lava," the simple childhood game that has only one rule: You can’t touch the floor. But as Quartz reports, a new paper contends that the game wouldn't have come about if it weren’t for the rise of American suburbs.

Published in the Social Science Research Network, the analysis by Tim Hwang of the MIT Media Laboratory argues that architecture was a vital factor in the spread of the folk game.

In the new suburban housing developments of postwar America, builders began to market the relatively new idea of the family room, an informal room designed for the social needs of the whole family. This room was separate from the formal living room and dining room, both of which were more likely to contain the inhabitants’ good furniture and fancy china. In building plans popular in the 1950s and 1960s, they were also set apart from the kitchen. One 1965 poll found that seven of 10 new houses built that year contained a family room.

And these factors, Hwang argues, are integral to playing The Floor is Lava. Family rooms provide big couches, coffee tables, and other furniture that kids can move around, climb on, and use as props for the game. Bedrooms would be too small, and formal living and dining rooms too full of potentially fragile items that Mom and Dad would be livid to find disturbed. And kitchens were seen as a mother’s domain, meaning that she would likely be there to put a stop to any shenanigans.

"What is unique about the family room space is both the quantity of space and permission that it affords to the play of The Floor is Lava,” Hwang writes.

However, this is just a hypothesis, and no one can really identify who started playing the game first. Kids in urban apartments can also theoretically jump all over their parents’ living room furniture, if allowed. During my childhood, the game typically took place on a playground rather than inside, requiring players to avoid the ground rather than the family room floor. There are games that originated elsewhere in the world that also revolve around avoiding the floor—Hwang notes examples from Kenya and the UK. But given how the spread of suburbs in the U.S. during the postwar period affected home design, it makes sense that a game might arise from the new spaces children lived in. We may never truly know how The Floor Is Lava was invented, but architecture seems like a good clue.

[h/t Quartz]