UPDATED July 31st, 2018 

Universal birth order traits aren’t just mythology. Austrian psychiatrist Alfred Adler is considered the father of birth order psychology and his theories are the basis of just about all modern thinking on the subject. A new study of 377,000 high school students found that there is some truth to the stereotypes but the differences may be so minor that they don’t have much of an effect in real life. Of course, birth order is just one variable and as the University of Illinois psychology professor Brent Roberts, who led the analysis with postdoctoral researcher Rodica Damian points out, “Another major problem with within-family studies is that the oldest child is always older. People say, ‘But my oldest kid is more responsible than my youngest kid.’ Yes, and they’re also older.” Good point!

Still, it’s always fascinating to ponder how birth order psychology affects our personalities now and parents often feel it acutely as their family grows. Here are 10 surprising birth order traits you may not know.

Read Related: Sibling Relationships: How to Tighten the Bond with Your Sister or Brother