How many times did your mother tell you this growing up? Well, it turns out that it’s true. Have you ever seen a gorgeous person who opened his or her mouth and spewed out venom that made you completely change your mind? Apparently so have the subjects studied by Gary W. Lewandowski and his team of researchers at the Monmouth University.

The bottom line is inner beauty matters … a lot .. even when we’re looking packaging, we care about contents. Researchers found that personality actually affects how we perceive physical attractiveness.

Conducted in 2007, the study had participants view photos of members of the opposite sex and rate their attractiveness. During round one, the participants were not given any information about the models’ personalities. But, in round two, they were told about character traits—positive ones like honesty and kindness, and negative ones like rudeness and prejudice. The result was that it greatly influenced how beautiful and romantically desirable raters considered the models to be.

So, your mother was right and let this be a reminder that pretty is as pretty does. Your personality will go a long way toward determining your attractiveness; it can even change people’s impressions of how good-looking you are.