Parents all over the world strive to treat all their children equally, but according to a study from the University of Edinburgh, there might be an unrealized benefit to being the first-born.
The study, published in Journal of Human Resources, found that while all children were given the same level of emotional support by their parents, first-borns were more likely to receive help with skill-developing tasks, as well as more mental stimulation all-round.
This then leads to higher IQs as compared to their younger siblings, according to the Guardian.
In an attempt to explain what they call the "birth order effect"--children born earlier in a family tend to have higher levels of education later in life, as well as higher salaries--researchers observed about 5,000 children from pre-birth to age 14, with the children assessed every two years.
The researchers also took family backgrounds and economic conditions, as well as other environmental factors into account.
Dr. Ana Nuevo-Chiquero of Edinburgh University's School of Economics stated that, "our results suggest that broad shifts in parental behaviour are a plausible explanation for the observed birth order differences in education and labour-market outcomes."
The study found that not only are first-borns more likely to have higher IQs, but mothers were more likely to take part in risky activities, such as smoking, while pregnant with the subsequent children.
Still, not everything is perfect for first-borns as a study published in the Journal of Economics and Human Biology found that in comparison to their younger siblings, "first-borns are less healthy in terms of physical markers such as blood pressure, triglycerides [a type of fat found in blood], and indicators of overweight and obesity".