In 1955, a researcher named Asch did a scientific study about group behavior
In his study, he found that, in a group of a hundred people that had a wrong answer to a question, a small number who had the right answer chose to go with the incorrect ones, even though they had proof it was wrong
Asch, Solomon E. "Opinions and Social Pressure." Scientific American 193 (5) (Nov. 1955): 31-5.