By Nicole Brewer and Ray Boyd

PHILADELPHIA (CBS) — First-born children often cite the advantages given to their younger siblings, but according to new research they have the advantage when it comes to intelligence.

A new study from researchers at The University of Edinburgh found that first-born children have the mental edge and that could be due to mom and dad.

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According to the research, that edge shows early. First-born siblings on average score higher on IQ assessments than their siblings by age 1.

Researchers sought to explain this advantage which they say leads to better wages and higher levels of education for first-borns. Five-thousand children were observed from before their birth to age 14 and assessed every two years. Reading, math, matching letters and vocabulary were among the fields observed.

Parental behavior was also observed and linked to children’s test scores.

The study concluded that parents change their behavior as they continue to have children. With the first-born they take part in more activities that stimulate the mental growth of the child such as reading and crafts. Those type of activities do not occur as often with subsequent children.

“There’s a little more effort put into first born child,” said Natalie Sabzghabaei of Philadelphia.

“You have to take it with a grain of salt,” said Dr. Frank Farley, a psychology professor at Temple University. He says the findings are legitimate, but may not predict future success.

“We know that your emotional side, your motivational side, relationships, how you deal with life socially, these are profound factors in success.”

Farley believes the merit of the study lies in what parents can learn from it.

“Cognitive games, puzzles, word games, interact with them verbally as much as you can. And try to do it for every child.”

The researchers also added that mothers took more risks during later pregnancies such as smoking.

The study was published in the Journal of Human Resources.