Since the 60s, a good amount of research has been done on Adler’s birth theory and middle children, but much of it is conflicting.

When considering why middle children are the way they are, one comprehensive book by two therapists titled The Middle Generation Syndrome notes, “If there are only three children, the first gets to be the oldest and the youngest gets to be the baby. The middle child may be left out […] The closer the children are in age, the less energy the parents may have had to give, exacerbating the problem.”

And there is some research suggesting that birth order might influence personality and mental health: For example, after analyzing 404 children, one 1988 paper in The Journal of Genetic Psychology found that first-born children were less likely to suffer from depression and anxiety than middle and younger children. They also tended to report higher levels of self-esteem.

But for every study finding that birth order traits are legit, there’s one that concludes they aren’t.

One 2015 paper titled Examining the Effects of Birth Order on Personality states, “we consistently found no birth-order effects on extraversion, emotional stability, agreeableness, conscientiousness, or imagination […] We must conclude that birth order does not have a lasting effect on broad personality traits outside of the intellectual domain.”

In response to this research, another study boldly titled Settling the debate on birth order and personality concludes that “birth order has little or no substantive relation to personality trait development and a minuscule relation to the development of intelligence.”

So, middle child syndrome probably won’t be a bonafide medical diagnosis anytime soon. But that’s not to say that middle children can’t relate to the common traits of “middle child syndrome,” or benefit from paying attention to them. Here’s some background on what they are, and how to use them to your advantage.