My three baby cats (they're actually almost two years old now but that's the only way I know how to distinguish them from their mother) all have distinctive tails.

Big Mac has been identified by the vet as being part Manx because the last couple of vertebrae feel "knotty". I first noticed it when he was only days old and thought maybe his mom had stepped on him and broken it!

Cookie almost always holds her tail sideways, in an upside down "U". I almost never see the straight up, or the "?" mark that most cats hold their tails in. When I pet her back or butt, she just flips her tail right over my arm!

Pepper usually holds her tail in the "?", but the two curved halves nearly meet! In fact, I can easily fold her tail in two, or make the Dairy Queen curlicue out if it and she shows no discomfort at all.
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Margaret - that is too cute!