Hackers who stole information from the U.S. Office of Personnel Management could have taken as many as 21.5 million people’s Social Security numbers, including those belonging to spouses and children of workers. Officials have said they strongly suspect the hackers are from China. The agency announced Thursday that anyone who underwent a background investigation since 2000 is “highly likely” to have been affected (and people checked before 2000 are at risk). More than 1 million individuals’ fingerprints were also in those files. The breach is six times as large as what OPM first said in June. OPM contractors working in China and Argentina had direct access to computer networks.