She explained that many people, but especially women, feel fraudulent when they are praised for their accomplishments. Instead of feeling worthy of recognition, they feel undeserving and guilty, as if a mistake has been made. Despite being high achievers, even experts in their fields, women can't seem to shake the sense that it is only a matter of time until they are found out for who they really are- impostors with limited skills or abilities.
Sheryl Sandberg (2014). “Lean In for Graduates”, p.37, Knopf