Hey there! Hello!
I would say this statement is false false false. As someone who went through adolescence not that long ago, I can say with certainty that both physical and mental changes are yielded from the process. During this time, kids tend to start growing hair places, grow taller, start getting deeper voices, and go through physical changes related to reproduction.
There's also a lot of other stuff that goes on in their heads, too. Hormones start kicking into high gear, meaning a lot more emotion will be felt than ever before. Kids will start to really consider their identity and who they are, as well as things like their sexuality and who they are attracted to, especially in today's day and age where kids have a lot more exposure to that kind of stuff. Kids may also really start to think about why their reproductive organs are changing so much, which can bring on a lot more emotion and urge on top of emotion and urge.
Hope this helped you out! Feel free to ask me any additional questions if you have any. :-)