One can't even say that good circumstances are always better than bad circumstances. Bad circumstances can teach a lot about humility, perseverance, empathy, compassion, etc. Good circumstances can lead to grown, spoiled children, people with a child's concept of how the world works, people with no consideration towards others because they didn't need to be part of a community, etc.

Environment plays a huge role, but it's somewhat unpredictable what lessons are taken. One could also say that it's not unanimously clear what makes a good environment; it's likely not simply about having resources and lacking conflict. Likely an amount of scarcity and conflict are needed.

All this isn't to say that kids are all born the same, but I don't consider such differences to generally matter as much as the effect the environment can have.