Dear Prudence

Prudie chats with Lizzie O’Leary, host of What Next: TBD, about a sibling with some bad intel.

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Each week, exclusively for Slate Plus members , Prudie discusses a new letter with a fellow Slate colleague. Have a question for Prudie? Submit it here .

Dear Prudence,

My sister was dating Dave and everyone was convinced he was perfect for her—she even confessed to me that she was pretty sure he was “the one.” Everything seemed to be going great … until I found Dave’s profile on Grindr. I showed it to my sister and she broke things off with Dave. This was six months ago.

Well, I ran into Dave recently and he was with someone who could have been his identical twin. He introduced me to his cousin Trevor.

When I met Trevor, I felt a pit in my stomach, but I wasn’t sure why.…