London’s Daily Mail published a roundup of sources indicating that not having a Facebook account is “suspicious.”
For example, the article refers to a Forbes.com report that:
Human resources departments across the country are
becoming more wary of young job candidates who don't use the site. The common concern among bosses is that a
lack of Facebook could mean the applicant's account could be so full of
red flags that it had to be deleted.

The Daily Mail also refers to a recent article in the German magazine Der Tagesspiegel that noted:
Neither the alleged Aurora movie-theater
shooter James Holmes nor Norway’s Anders Behring Breivik had Facebook
accounts.
For the record, I don't believe not having a Facebook account makes you more likely to be a mass murderer.
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