Am I correct to read this as "children invest more brain power into their parents than the parents into the children only if the parents neglect the children"? This sounds fallacious. First it would imply that children that don't invest more brain power into their parent don't have neglectful parents which surely isn't right. The children could try to find other caretakers. Second if parents have more than two children they have to split their energy more than the child has to split. And this would imply that parents with more than two children were necessarily neglectful which I also can't see.