WOW... I guess my first thought is everyone in the documentary seemed to have lied (or changed) their story over the series.
Next biggest question is they did an informal comparison to another child when Natalia was "6". Has there ever been a formal comparison with others as she has aged?
It really comes across that there was bad behavior on both sides, but as parents the Barretts should have done better. Where are Kristine may have ran the house, Michael should have did better. While I understand his desire to pass the buck, it was just sad to watch his meeting with Natalia.
Documentaries like these help "normal folks" to understand the world we really live in.