 However, simply focusing on contemporary western or western-influenced cultures, cannot answer the question of 'universality'.For example, if our hunter gatherer ancestors or historic agrarian cultures had different patterns of behaviour this would suggest that 'teenage rebellion' is not 'completely natural'.In "Scientific American", however, Harvard psychologist Robert Epstein disparaged the notion of "the immature brain that supposedly causes teen problems" as largely a myth, and wrote that the turbulence often seen as typical of these years is not "a universal developmental phenomenon."