People share the 18 things that are a 'subtle sign' someone is really smart (upworthy.com)
One of the strangest things about being human is that people of lesser intelligence tend to overestimate how smart they are and people who are highly intelligent tend to underestimate how smart they are. This is called the Dunning-Kruger effect and it’s proven every time you log onto Facebook and see someone from high school who thinks they know more about vaccines than a doctor. “Such findings imply that, in order to be adaptive, first impressions of personality or social characteristics...