Okay so I've had a thing with this guy for about a month now and I'm starting to catch sly feelings. I recently found out that we're really distantly related- like cousins 4th/5th removed and through marriage- we haven't had sex but shall I tell him? Just call it off or simply ignore it?
Have a conversation with him & let him know what you found out. I wouldn't suggest you keep that to yourself as it's just unfair & will eventually play on your mind.