Parents who are footing more of the college tuition bill for their children give them a better chance of graduating. But a surprising new study finds they may not be doing them any favors in another area — generous financial support appears to lead to lower grades.

The study, published in this month's American Sociological Review, suggests students with some of their own "skin in the game" may work harder, and that students with parents picking up more of the tab are free to take on a more active social and extracurricular life. That may be fun and even worthwhile, but comes at a cost to GPA.

"It allows for a lot of other activities in college that aren't academic," said author Laura Hamilton of the University of California, Merced. "Participation in the social scene is expensive — money to hang out, drink." But "the more you have all these extras, the more you can get dragged into the party scene, and that will drag down your GPA."