That's the verdict of German scientists writing in the journal Vision Research, who say when you're seen with people older than you, other people will think you're younger than you are.
The psychologists from Jena University claim you can change the way you see someone by looking at other people. So if, for instance, you look at a photo of an older person, then a photo of someone who's 30, you will probably underestimate the age of the 30-year-old. And vice versa.
In fact, that's exactly what the researchers did. They asked 24 young adults to look at photos of women and men. But if they showed them faces of older people first, they estimated the ages of the people in the original photos as substantially younger than they were.
The effect was more significant if the older faces and younger faces viewed one after the other were the same gender too - though even when the genders were mixed, people still underestimated the ages of the younger people in the photos.
You've got to admit it's a fascinating idea. Expect grannies to be in huge demand once more people realise that hanging out with older people can make you seem years younger in the eyes of others.
What are your tips for looking young?