This one is sure to stir up some sibling rivalry. 

A new study by the National Bureau of Economic Research finds that first-born children get better grades. 

According to the study, parents are usually stricter with the first-borns and get a bit more lax when it comes to enforcing TV rules, monitoring homework, and even getting upset over bad grades for subsequent children?

What do you think?  Are first-born children smarter?  Do other factors have more to do with determining intelligence?  Sound off!