The cover article for last week’s Time Magazine was about sibling rivalry. Specifically, how parents favor one kid over the others. According to Jeffrey Kluger, who just published a book on this topic, all parents have favorites.

To illustrate this fact, he talks about how researchers went into a home specifically to observe if they could tell the parent’s favorite. So parents knew what was going on, and still, within a few hours researchers could tell in roughly 70% of the cases. And here’s more damning evidence for parents: grown siblings seldom disagree on who was the favorite.

Of course, favoritism is damaging to the non-favorite. But the favorite suffers as well, because the siblings resent the favorite.

Psychologists say the best solution is for parents to hide favoritism as much as possible. Which means I will not write about my own situation in this regard. But I will say that my nine-year-old was drawn to the title of the cover, which read: Mom Likes You Best.

He picked up the magazine and started reading. I thought: This is good. My kid is reading the science section of Time magazine. I helped him divide the article into manageable sections. But I’ll tell you, his reading level miraculously went up five grades in order to figure out who is the favorite in our family, which strikes me as evidence that kids are hugely motivated to learn when the topic interests them.