Don’t blame mental illness for mass shootings. Blame men.

So, what’s going on? According to sociologist Eric Madfis, the male gender-mass shooter connection may stem from cultural standards of how men are expected to react to stress and perceived victimization as compared to women.

“Women tend to internalize blame and frustration, while men tend to externalize it through acts of aggression,” says Madfis, who is an associate professor at the criminal justice department at University of Washington-Tacoma and author of a 2014 journal article exploring the intersectional identities of American mass murderers.

This isn’t just because of how men are built physically. While it’s true that having higher testosterone is often related to aggression, recent research indicates that testosterone is likely a result rather than a cause of violent behavior. This suggests that societal influences probably play a larger role in violence than any biological factor. After all, our culture is saturated in messages—whether in the media, in our military, in sports, at the workplace, or in our education and health care systems—that embrace and even endorse a distorted view of masculinity, which tends to value and encourage expressions of aggression by men.