Humans aren’t the only ones who are more likely to be bullies if they had a tough upbringing. 

Researchers in the Galapagos Islands noticed that a certain breed of seabird would beat up on nestlings whenever their parents would go out to look for food. The adult bird would peck, bite and bully the younger birds until they were bleeding. The researchers watched the birds for three breeding cycles, and what they found is that the young birds that were harassed as they grew up, became bullies themselves.

And that’s exactly what psychologists have found about humans, and the two problems might have the same root cause. Scientists believe that when we’re picked on as children the stress hormones in our brain surge, and that continued surge of hormones can permanently alter your brain chemistry. It impacts how you learn, and how you deal with emotions. Researchers say that watching the behavior of birds may help them figure out exactly how it works in humans, and find a solution to the cycle of bullying.