By Jennifer Valentino-DeVries and Michael H. Keller, The New York Times For her 18th birthday in March, “Jacky Dejo,” a snowboarder, bikini model and child influencer turned social media entrepreneur, celebrated on the secluded island of Dominica. On Instagram, she appeared in strappy swimsuits, basking luxuriously on a black-sand beach and floating in a jungle stream.

Her fans — thousands of men had been following her through her teens as she posted and sold photos — wished her well and eagerly anticipated her next move online as an adult. “Happy birthday,” one wrote in French. “I can’t wait to see you without any clothes on.

” Born two years after the launch of Facebook, she belongs to the first generation to grow up with social media and the multibillion-dollar creator economy that is redefining adolescence for girls. A Dutch citizen — her real name is Jacquelina de Jong — she has lived in more than a half-dozen countries and picks up languages with ease. But she is equally at home on the internet, where she has built a global fan base that is dominated by American men.

At 16, with the consent of her parents, she was pulling in upward of $50,000 some months, she said, charging for access to her online posts and images. When The New York Times began investigating the culture of underage girl influencers more than a year ago, Jacky Dejo — or simply Jacky, as she is widely known by her followers on the internet — quickly emerged as a prominent and eni.