Facebook users are inadvertently revealing many of their most personal secrets and personality traits through their “likes,” according to a University of Cambridge study that will likely raise fresh concerns about privacy and online personalization.“This study demonstrates the degree to which relatively basic digital records of human behavior can be used to automatically and accurately estimate a wide range of personal attributes that people would typically assume to be private,” the researchers wrote in their report, which was published Monday in the journal Proceedings of the National Academy of Sciences (PNAS).