Today’s most shocking story comes from a piece of research from Nielsen subsidiary NM Incite. Would you believe it: the most popular reason to add someone as a Facebook friend is because you know them in real life? Who knew? “Research suggests that real world interactions drive online friendships,” notes Nielsen’s blog post. Having mutual friends is the other popular factor – 60% of people surveyed cited this – well ahead of business networks (11%), and physical attractiveness (8%). The study also digs into why people unfriend others too. 55% say offensive comments are the cause, while 41% say ‘don’t know well’, and 39% are put off by friends who try to sell them something.