While having a college fund has long been considered a necessary boon for attaining a good education after high school, a new study has found that the more that a student’s parents shoulder the financial burden of college, including when costs are shared with the students themselves, the more the student’s grades decline.

The study, More Is More or More Is Less? Parent Financial Investments During College, was conducted by Dr. Laura Hamilton of the University of California at Merced, which was posted in this month’s American Sociological Review. While Dr. Hamilton’s study did confirm that students of affluent backgrounds were far more likely to go to college than others, the study also found something surprising: a greater amount of financial support given by parents lead to lower grades.

Although Dr. Hamilton also found that students of more renowned colleges and universities, such as those in the Ivy League, tend to show less of an impact on grades than other schools, the effect that a parent’s financial support has on a student’s grades can be found across every form of undergraduate institution.  While students of wealthy backgrounds being more likely to graduate, Dr. Hamilton believes that this result is likely due to students paying their own way through college having to leave school for financial reasons rather than a lack of commitment.

“It’s a modest effect, not big enough to make the kid flunk out of college,” said Dr. Hamilton in an interview with the New York Times. “But it was surprising because everybody has always assumed that the more you give, the better your child does.”

The reason for this unexpected phenomenon, says Dr. Hamilton, may have something to do with how students who have to pay for their educations themselves take the endeavor more seriously than those who never had to worry about how it would be paid for. According to Dr. Hamilton, her interest in how economic background effects the assiduity of students came from a year spent living in a college dormitory and observing the behavior of different students and interviewing their parents.

“Oddly, a lot of the parents who contributed the most money didn’t get the best returns on their investment,” she said. “Their students were more likely to stay and graduate, but their G.P.A.’s were mediocre at best, and some I didn’t see study even once. I wondered if that was nationally true, which led me to this quantitative study, which found that it is.”

The study compared the financial contributions of parents and their children’s grades, while controlling for economic background, by examining three seperate sets of data compilled on the federal level: the Baccalaureate and Beyond study, the National Postsecondary Student Aid Study, and the Beginning Postsecondary Students Study.

“There were some affluent families who thought their children were spoiled and didn’t pay the whole cost, and there were some families who had scrimped and saved and borrowed from family members and taken out loans,” she said. “And the affluent families aren’t hurt the most by the lower grades, because they had the connections to call the head of NBC or the N.F.L. and get their child a job. It’s more of a problem for the middle-class parents, who worked hard to pay the college costs, used up their retirement funds and are out of money by graduation time.”

In the end, the study showed that the students who performed the worst had parents who never established rules and expectations about working hard and maintaining a high GPA in order to receive financial help from them. As a result, Dr. Hamilton believes that parents looking to help their children pay for their education need to discuss the level of responsibility a student must take in their education before signing the check.

“Ultimately, it’s not bad to fund your children,” Dr. Hamilton said. “My kids are little, but I plan to pay for them — after we talk about how much it costs, and what grades I expect them to achieve.”