The recent article by the New York Times equated the power of password sharing to having sex among teenagers. It’s a form of affection or the ultimate sign of trust that enables one to read the others private emails and posts. In a 2011 telephone survey, the Pew Internet and American Life Project found that 30 percent of teenagers who were regularly online had shared a password with a friend, boyfriend or girlfriend. The survey, of 770 teenagers aged 12 to 17; found that girls were almost twice as likely as boys to share.
The essence of the article is that there is so much social pressure to comply that despite the negative fallouts of violating the privacy of other people who send mail thinking only the recipient can read them, emotion impact of reading mails when the relationship sours, jealousy and ability to slander through a personal account the trend continues.