The 19-year-old model, who was named as one of 25 most influential teens in 2014, shared her opinion about the topic of youth in a column for Wall Street Journal magazine.
"I feel like I grew up too fast a long time ago. Having older siblings, you grow up around adults, so you mature more quickly.
"I saw my sisters and parents working every day, so I was pretty much brought up to be a workaholic. But I just turned 19 a couple weeks ago, and I'm scared to be 20-it's the first step out of being a teenager," she wrote.