I told her, the child is experiencing "Youthful exuberance" which is normal for teenagers. This behavior can manifest in different forms, such as high energy levels, risk-taking behavior, and also desire for independence.
Nowadays, lack of limits imposed to teenagers and lack of respect displayed by teenagers is considered normal even from the biological perspective, since the science says their brains aren't totally developed yet, therefore they tend to have such noxious behaviors mentioned by you.
However, why teenagers from previous generations weren't exactly like this? Responsabilities were taken since an early age, traditions were important, and what the elders had to say and advise mattered. Now these teenagers are writting the rules, as there wasn't anything to consider before their existence. They are the pinnacle of ethics, morals and everything they defend must be accepted by society.
This phenomenon is more evident in the Western world, so no surprises why it's so decaying from a social and fraternal point of view. If you want to avoid this plague from falling over your heirs, make sure to educate themselves with timeless values, which transcend the trends of the modern era, and the barbarism of ancient times.