In the US we also use the phrase "type A" to describe someone who is very fastidious or anal-retentive, but I've never known it to be related to blood type. Wonder if it shares roots?
Some cultures believe that blood type has a bearing on personality [1]. I always thought "Type A" personalities were called so because A is the first letter in the alphabet. No idea whether I'm correct though the Wikipedia article says that BTPT is "not to be confused with" this so I'd imagine the overlap is coincidental.
alexjplant|17 days ago
[1] https://en.wikipedia.org/wiki/Blood_type_personality_theory