If you've got a rivalry going on with your siblings, the results of a new study will give you a bit of an edge.

We're all familiar with the stereotype that older siblings are more responsible and obedient, while the younger ones are often seen as boisterous. Well, this may actually be more than a stereotype.

For decades, researchers have been studying the birth order phenomenon to better explain why siblings raised in the same environment don't always turn out the same. Obviously, personality is a factor, but it turns out, parents are unknowingly raising their children differently.

Last year, researchers from MIT, Northwestern University and the University of Florida discovered that second-borns are more likely to become criminals. The reason is that parents of two or more, pay less attention to their younger children because they're too busy trying to focus on one child at a time.

"Despite large differences in environments across the two areas, we find remarkably consistent results: In families with two or more children, second-born boys are on the order of 20 to 40 percent more likely to be disciplined in school and enter the criminal justice system compared to first-born boys even when we compare siblings," the study's authors explained.

Now, a new study from the University of Edinburgh in Scotland has found that older siblings, specifically first-borns, tend to be smarter than their younger siblings.

"First borns score higher than their siblings in IQ tests as early as age one, the study has found," the researchers reported.

Why? Again, it all comes down to parenting.

Just like the previous studies, this recent one also found that older children often receive more intellectual support from their parents.

"Although all children received the same levels of emotional support, first-born children received more support with tasks that developed thinking skills," the researchers wrote.

As the oldest child, I've always scored better grades than my younger siblings, and suddenly everything makes a lot more sense. Also, according to the findings, increased thinking skills could explain why older siblings also tend to be better educated with successful careers and higher pay.

"Researchers found that parents changed their [behavior] as subsequent children were born. They offered less mental stimulation to younger siblings also took part in fewer activities such as such as reading with the child, crafts and playing musical instruments," the University of Edinburgh explained.

Additionally, the study noted that "mothers also took higher risks during the pregnancy of latter-born children, such as increased smoking."

So this explains why my mother never let me jump in muddy puddles, but this wasn't the case for my brothers and sister, who came after me.

Parents also have higher expectations of their first-born child, and as noted by British psychologist Francis Galton in 1874, parents often view their oldest child as a companion. This means that they're subjected to more pressure and undertake more responsibility than their younger siblings. All of which translate into how well they do at school, work, and life overall.

Are you the oldest or younger sibling? Do you think there's some truth to this study? We'd love to hear your thoughts.