Nobody ever did a full A/B study on that, it would require damaging many babies for rest of their lives. We're over Mengele's approach for quite some time and time machine isn't a thing yet.

But there are tons of stories that babies neglected/suffering perform much worse for rest of their lives. Deep mental issues, lower IQ etc. Some proof might be stories I read from some specifically cruel communist Romania orphanage, where children were neglected, often caged or chained. Something like 90% of them struggled significantly in the society in their later lives.

> Nobody ever did a full A/B study on that, it would require damaging many babies for rest of their lives. We're over Mengele's approach for quite some time and time machine isn't a thing yet.

It doesn't have to be interventional study.

> But there are tons of stories that babies neglected/suffering perform much worse for rest of their lives. Deep mental issues, lower IQ etc. Some proof might be stories I read from some specifically cruel communist Romania orphanage, where children were neglected, often caged or chained. Something like 90% of them struggled significantly in the society in their later lives.

Children being caged and chained having long lasting consequences is so far from from the original claim that first 3 years of our lives are most forming on our deeper personalities. It appears there is no reason to consider that claim true.