On Friday, Science published a study conducted by Norwegian doctors on 250,000 military conscripts. The study found that eldest children enjoyed an IQ boost of nearly 3 points.

The study’s finding that psychological factors — interaction of parents and children — and not biological ones account for the IQ discrepancy is fueling a raging debate this week. It will no doubt rile existing sibling rivalries and cause conscientious parents like mine to second guess every interaction they had with us growing up. Did they give us all equal attention? Did they show favorites? Did they ignore someone’s hidden talents? 

Let’s explore. I am the oldest of 4 children. My parents took twice as many photos of me and saddled me with all of the responsiblity and expectation you expect of a first born. I attended a presitigious public university and graduated with a humanities degree. My younger brother, more introverted and more modest, graduated with a BS in electrical engineering from one of the nation’s top programs and is currently finishing his Masters degree in mathematics. The older of my two sisters received her Bachelors and Masters degree from one of the nation’s best accounting programs and was also captain of her NCAA Division I gymnastics team. My youngest sibling, also a gymnast, who by the study’s method should probably be the least intelligent, is about to start her PhD program in biomedical engineering. (Disclaimer: neither I nor any of my siblings are Norwegian military conscripts.)

On paper at least, you can see why I would be reluctant to test the doctors’ findings with an IQ test. I know none of my siblings would care. The only persistent rivalry is a bet my brother and I made a long time ago: whoever has the most hair and whoever is the tallest at age 35 wins. Height and hair seem to be far more substantial than 3 IQ points.