If all it took to ensure a good outcome was to create good circumstances, we'd have fixed society in the prehistoic era. People would have figured it out and asked the good parents to raise all the kids one generation, and problem solved.
Instead what you see is parents with five successful kids, and one that keeps ending up in prison, and no one can really explain how it went wrong.
We have indigeous people and historic effidence, that kids with mental health issues were kept hidden from the rest of a village, sometimes in cages and on chains.
We know very well that the education system around the planet cateres to the masses not to the ones with disabilityes, ADHD etc.
Human beings are complex, any education system is not and its not reflecting the diversity of humans.
In japan for example, kids have to cleanup there own class rooms, wonderful concept, any other real country which adopted that?
Equal parents doesn't need to mean equal circumstances. Times and culture change, parents age, family circumstances change over time, their environment outside the home is different, different friends, different experiences, etc. There's a myriad of factors that can lead to very different circumstances for siblings.
If you talk to people working with foster kids about why some kids succeed despite everything stacked against them, they'll tell you some kids are different.
It's possible you're correct and there's some circumstance controlling things we can't see or don't understand, but that's not a testable idea.
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.
They haven't had these kids from the beginning. This statement doesn't refute any environmental issues.
Nonetheless we know that humans are neural networks. These are formed. There is something inbetween the initial setup and your human in prison which lead to this or something missing which lead to this.
Instead what you see is parents with five successful kids, and one that keeps ending up in prison, and no one can really explain how it went wrong.