BIG DATA: Study: Facebook 'Likes' Can Be Used to Accurately DetermineIndividual Differences.
 

"Simply by delving into volunteers’ Likes, the researchers could
determine in 95 percent of cases whether a person was Caucasian or
African American and in 88 percent of cases whether the person was
heterosexual or homosexual. They could determine whether the person is
Christian or Islamic 82 percent of the time...."