It has been a long standing school of thought that if you hire heavily through referrals, diversity within an organization suffers. Since referrals only account for less than 10% of the average applicant pool, they can not be solely responsible for killing an organization’s diversity. However, the general perception was founded on the basic principle that people tend to gravitate towards, and maintain circles of association, with people who they feel are “like them.” This is a very basic unconscious bias that begins in childhood (think about your old high school lunchroom) and continues into adulthood.