The human brain is hardwired to judge. This survival mechanism makes it very hard to meet someone without evaluating and interpreting their behavior.
While we tend to think that our judgments are based on the content of conversations and other obvious behaviors, the research says otherwise. In fact, the majority of our judgments are focused on smaller, subtler things, such as handshakes and body language. We often form complete opinions about people based solely on these behaviors.
We are so good at judging other people's personalities based on small things that, in a University of Kansas study, subjects accurately predicted people's personality traits, such as extroversion/introversion, emotional stability, agreeableness, conscientiousness, and openness, simply by looking at pictures of the shoes they wore.
Our unconscious behaviors have a language of their own, and their words aren't always kind. These behaviors have likely become an integral part of who you are, and if you don't spend much time thinking about them, now is a good time to start, because they could be sabotaging your career.