It’s no surprise that humans dislike greediness. But a study in the August issue of the Journal of Personality and Social Psychology found that people sometimes punish generosity, too.

The subjects played a computer game where opponents put points (worth money) into a common pot. Afterward, subjects often voted to kick out of the group computer-controlled players who put in more points and took less than the others.

Perhaps people recoiled because the overgivers violated social norms—rules are rules, even if breaking them benefits everyone—or because they set high standards that players are reluctant to measure up to. Because of our natural aversion to inequality, the study authors say, we sometimes find generosity as annoying as selfishness.