How can criminalising children harm the child development?

Criminalising children can harm them in many ways. Growing up in a locked cell stops the child from the necessary, normal social communications he needs to develop himself so the child can result in self-isolation and generally more faraway from the mainstream of the society. Furthermore, criminalising children makes children feel "different" and frustrated and this can lead to depression and lots of other psychological problems that stunt children's growth. When children commit crimes, people should realize that children are still in a developing state of mind so they are probably not aware of what they have done or how serious the crime is. So the best way is to give them time and let them learn, instead of making them criminals and stunting their growth and vision even more.