One of the stranger effects of the COVID-19 pandemic was the shortage of toilet paper on grocery store shelves. In hurricanes and winter storms, we often see runs on milk, bread, and bottled water. But toilet paper? Well, we now know who has been hoarding all of it.

In a study published Friday in the journal Plos One, researchers looked at whether different personality traits were associated with toilet paper hoarding.

It turns out that toilet paper stockpilers tended to be more anxious and fearful about the coming COVID-19 threat compared with those who didn’t stock up. This personality trend was consistent in all 22 countries the researchers studied.

One explanation is that people who are anxious hoarded toilet paper because it gave them a sense of control during a health crisis in which we had little control.

Others likely to hoard toilet paper included people who scored high in emotionality. These are people who tend to be more fearful, anxious, dependent and sentimental.

Maybe surprisingly, people who are conscientious, organized, perfectionistic, diligent, and prudent, also tended to stockpile toilet paper.

Should we be upset with these hoarders? Well, you could argue that they were doing it out of fear, so we should empathize with them, not admonish them. You can decide.