If a child does not have the proper nurture that is required they will not develop properly. If they live a life of isolation their brain will develop without the essential social skills they need and once the brain is too developed you cannot change what it thinks. The child will not be able to do things like form complete grammatically correct sentences or phrases and will be physically,mentally, and emotionally behind everyone else that is around them when they are reintroduced into society. This is also known as a feral child.
If a child's physical environment is not a recommended way of living (for example: house is completely cluttered all the time, mother/father/both are hoarders who keep everything that comes in), then the child likely grows up accepting that and thinks it's okay. Or if they grow up in a neighborhood where gangs exist they might accept that too. OR they rebel and end up wanting or working for a better life.
These are just examples, the situation doesn't have to be exactly what I listed :)
Compared to good schooling and community the child will be happy with his environment