Want to Feel Bad? Ask TikTok How Old You Look.

Cherri Gervais got her first gray hairs as a teenager.

“It’s genetic,” she said.

Her hair color, a striking shade of silver, is the first thing people on TikTok noticed when she asked them to tell her how old she looked in a recent video.

The guesses ranged wildly. Many were correct, or close enough, Ms. Gervais said. (She turned 34 this month.) Other suggested she was in her 60s or 70s.

Ms. Gervais, who lives in Kansas and works for a part-time beauty company, said she had decided to post her video after coming upon similar TikToks.

“I saw someone Gen Z do it because they were saying Gen Z is aging faster,” she said, referring to a recent online theory arguing that teenagers and young adults are aging more rapidly and more visibly than their millennial counterparts.

Her video is part of a trend in which users, mostly women, ask strangers to comment on their appearances. Ms. Gervais said that many of the comments she had received were unkind.