There is a feeling of ‘I’ve got a book to sell’ in the article.
Yes, there must be so many variables. Years ago I had friends who had two daughters, and then adopted a third. The adopted daughter, apparently given the same upbringing, went off the rails in a similar way to the family that she was taken from. They then raised her son, who did likewise. My friends are convinced it was a product of their genes, or DNA, or whatever. But I wonder whether their expectations were different, that they went in expecting trouble, and unwittingly and unknowingly the ‘problem’ children were treated differently.