When we think of blended families, we think of the "Brady Bunch."

But if the 70's favorite became reality, researcher Kathryn Tillman says the group that "somehow formed a family" would be dealing with a lot more than sitcom squabbles.

Kathryn Tillman is an Assistant Professor at Florida State University and her research has just hit big -- as it's been published in the journal Social Science Research.

But it's not just the study's publishing that's gaining interest, it's its findings too.

Tillman says adolescents living in blended families -- with half or step siblings -- have lower grades and more school related behavior problems than their peers.

"You get the situation where kids may feel more conflict, they may feel more in competition with each other. Parents are all the sudden having to shift attention and shift resources between children and that can be difficult for kids to adapt to," said Tillman.

School guidance counselors agree with Tillman's research.

However they say, with the proper precautions, parents can deal with major family structure changes by being honest with their children.

They recommend notifying your child's school if you expect any drastic changes in family structure.

"Children often feel when there's something of a crisis nature going on in their family that they are the only ones who ever have experienced it before and sometimes we'll have a group just so the kids can see that other kids are grappling with the same kind of problems they are," said guidance counselor Diane Scheiner.

According to the study, it's the boys living in blended families that appear to have the hardest time coping.

They're reported to having average GPA's one quarter of a letter grade lower than those who only live with full siblings.