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.
“People told me to dye my hair, told me to get lashes, to fix my eyebrows,” she said. Several suggested that she looked like a “middle-aged mom.” “There’s nothing wrong with that,” Ms. Gervais added. “But I’m not a mom.”
Jalisa Silva-Toney, a 21-year-old social work student who lives in Point Pleasant, W.Va., also took part. “I was just curious,” she said, noting that people often get her age wrong.
Part of the reason she wanted to post her video, she said, was that she hadn’t seen many other Black women participating. She added that TikTok’s culture of constant comparison could be fueling the trend and the larger debate over her generation’s frown lines and skin elasticity.
Pri Maha, a business analyst in Atlanta, said she had asked people to guess her age in a recent TikTok video mostly out of curiosity.
“I do see content from big-time influencers who are only, like, 23, getting Botox,” Ms. Maha, 27, said. “Sometimes it does make me think, ‘Oh, should I be doing that, since I am older?’”
She added, “I feel like there is definitely a push where I see younger girls getting work done, or just trying to look as young as possible, when they are still super young.”
Not everyone was in it just for curiosity’s sake, though.
“I have pretty thick skin, and not a lot of things hurt my feelings,” said Morgan Driscoll, who works in communications at a tech company and lives in Weymouth, Mass. “I knew it was worth posting for the views.”
Because she is someone who aspires to have a large number of TikTok followers, Ms. Driscoll, 30, saw participating in the trend as a kind of business opportunity.
“I didn’t post it because I was looking for validation,” she said. “I posted it because I knew it would get engagement.”
She was right: Her video has been viewed over 100,000 times.
Most of the comments were about her eyebrows. “I have very millennial eyebrows,” Ms. Driscoll said, meaning her eyebrows are thin. She was going to get them “fixed” this week, she added, based on the TikTok feedback.
“I think the worst I got was a comment saying that my neck is getting a gobbler, which is crazy,” she added. “I mean, I just turned 30!”
But for many TikTokers, any engagement is good engagement.
“A comment is a comment,” Ms. Driscoll said. “I don’t care if they are trolls. I don’t care if they tell me I look like a toad. I just want the comments.”