Do anti-vaccine people hang around with anti-vaccine people or did hanging around with them cause them to lose faith in science?

There are an alarming number of factors that all correlate with anti-vaccine sentiment; the types of food purchased, beliefs about science, beliefs about energy, and beliefs about politics. But did all of those happen, and the people who embraced them gravitated toward each other, or did the social circle create the issue?

In Social Psychological and Personality Science, Michael Laakasuo, Anna Rotkirch, Venla Berg, and Markus Jokela write that while it is well known that people tend to form friendships with others who have a similar personality, they believe they have discovered a connection between personality traits and differences in friendship patterns.

Using the five factor personality model (extraversion, agreeableness, conscientiousness, neuroticism&openness to experience) they found that people high in openness are about 3% more likely than people low in openness to have friends who are different from them. People high in agreeableness and extraversion showed more traditional friendship ties.

The authors, from the Finnish Family Federation and from the University of Helsinki Institute for Behavioral Sciences, Finland, analyzed data on 12,098 people and their 34,000 friends from the British Household Panel Survey to investigate how people's personalities are related to various characteristics of their three closest friends.

Meanwhile, Russ Clay, a psychology professor at the College of Staten Island, says that higher feelings of disgust predict negative attitudes towards vaccines. In a pair of experiments, the connection between disgust and negative vaccine attitudes occurred in both student (study 1) and non-student (study 2) groups. The results support findings from other studies on the connections between the behavioral immune system and vaccine attitudes.