Sorry, I don't have a link for you, but I've recently read that one of the problems that many parents who live in poverty have is that they simply do not know what is necessary to be a good parent.
The specific example was with respect to talking to infants - that talking to children who do not yet have the power of speech makes an enormous difference in the development of verbal and cognitive ability. Rich infants heard an order or two more words per day than poor infants due only to the fact that poor parents didn't know that it was important. There was no intent to neglect, just ignorance.
The overwhelming majority of parents want to be good parents, some just need better information on how to do it.
I'd like to see your data on this and whether the studies they did corrected for genetics. A lot of these studies like where parents talked to their kids more and the kids ended up being smarter ended up being proven false because there was no 'control' in these groups, children who were adopted, etc. Check out Steven Pinker's The Blank Slate. This talk sums it up pretty well:
Overly enriched environments might or might not matter. But deprived environments in early childhood demonstrably hurts. A lot.
The cause is that in the first few years of life we lose unused connections between neurons. If a child does not have a primary care giver, then a lot of the connections lost are necessary for proper social and cognitive development, and the child is impaired for life in ways which are clear in the physical structure of the brain.
This has been known for decades, yet still periodically someone somewhere that still has orphanages rediscovers this basic fact. (The most recent example that I heard about involved children in Romania.)
I just watched the TED talk you linked to. Professor Pinker seems to completely dismiss the idea that parenting has a significant effect on the child. I wonder whether this study with rats has changed his mind - here's the relevant quote: https://news.ycombinator.com/item?id=5722596
The specific example was with respect to talking to infants - that talking to children who do not yet have the power of speech makes an enormous difference in the development of verbal and cognitive ability. Rich infants heard an order or two more words per day than poor infants due only to the fact that poor parents didn't know that it was important. There was no intent to neglect, just ignorance.
The overwhelming majority of parents want to be good parents, some just need better information on how to do it.