The theory begins, as many have done, on Reddit, where the original poster u/wintersparrow22 pointed out a small detail that might link Rachel and Chandler’s family: They both have a relative named Muriel. In “The One in Vegas Part Two” of Season 5, Rachel says she looks like her great aunt Muriel after she couldn’t clean Ross’s craft – beard and mustache – from face. Later, in Season 8’s “The One with Rachel’s Date”, Chandler finally reveals that the “M” in Chandler M. Bing stands for Muriel. He’s embarrassed by it but says it’s them, so we can assume one of his older relatives is named Muriel. Here’s what some of the other Redditors on the thread find plausible, with u / DisplacedNovaScotian note that it was an “excellent catch.”
Theoretically, if these are the same Muriel, they could be cousins - first, second, or otherwise. The OP pointed out their families’ similarities, writing, “I’m not aware of any other connections between the families, except that both families (Green and Bings) were close together and had amassed a large fortune, so there could be some understanding.” Plus, they lived so close together that Chandler heard rumors that a cheerleader at another high school was actually Rachel. .
u/wintersparrow22 admits that while a connection like this will probably pop up in the conversation at some point, “Chandler doesn’t reveal much about his family except for off-topic comments because of the topic makes him uncomfortable.” Chandler’s family was a sore point for him after his parents divorced. In retrospect, Rachel and Chandler’s kinship would have made their few kisses more awkward and added complications to their linked family, but they’d be in the same place.
https://www.looper.com/732577/the-rachel-and-chandler-fan-theory-that-changes-everything-on-friends/ Rachel and Chandler Fan Theory changes everything for friends