Thanks for putting in the time on this. These correlations are interesting to say the least. The one question however, that keeps coming to mind for me is the question of how 'better' is defined as we look at this from the perspective of children. Looking at what the data reveals on its surface, I would almost prefer having my daughter grow up in one of the countries mentioned on this list, but not so much for my son believe it or not. I also wonder how attainable and commonplace a rags to riches accent would be in these nations.
In my opinion, the statistics about the above countries that aren't broadcasted enough are demographical in nature. The demographic influence on a society is quite powerful and should not be overlooked when comprising such lists. How homogenous are the populations? How many divergent subcultural influences have a voice within the national landscape? Has there been a national somewhat coersive cultural assimilation put in place by governing bodies that dates back generations?
I'd venture to say the term "better" here simply means better in the ways you can realiably measure, for example infant mortality, education recieved on average, equality with other children concerning possibilities in their lives and so on.
The "rags to riches"-point is an interesting one. In the nordic countries heavy emphasis is put on that everyone recieve equal opportunities. Anyone, regardless of financial or cultural background, can become a doctor or lawyer, just to pick a few stereotypical ways to get well-off. In countries like the US, for every successful rags-to-riches person, how many actually tried it and failed?
Some statistics on this would be interesting, but I think the amount of people living in absolute poverty in the US say a lot about how it actually is. For every successful businessman, athlete, actor/actress, performer, there's scores and scores of people who just didn't make it.
I'd also like to see some statistical analysis on the way cultural diversity affects possibilities for children, or just people. I do however feel the need to ask you to clarify one point;
What do you mean by "homogenous populations"? I assume you mean culturally, but can't help wondering if you're meaning racially. Usually culturally is just a diplomatically correct way of saying racially, since most people readily think of caucasians when talking about sausage, and africans when talking about okra (Yes, I picked food culture because I'm hungry!

)
If the above is correct, and I'm not saying it is, then in what way does it matter what the people you grow up with look like? Isn't it the
personalities of people that we're interested in and should be focused on, not the exterior.
So I suppose the real question, then, is; what are the effects of cultural diversity on the development of children? I'm sure there's mostly positive effects, but I'd like to hear from someone who knows about this stuff.
Oh, and I'm sorry my intention is not to hijack the thread, please forgive my transgression.
Regards,
Wrec