I generally find it interesting that the demographic with concerns and making alternative choices with regards to vaccines and hospital-based childbirth is most often highly educated and likely higher g. The connection with longer breastfeeding and higher IQ interests me as well. I've found in my small group of friends with higher LOG kids that most went well beyond the average 6-9months that other around us were doing... Personally my son was 3.5yrs old when he stopped.
Re: nursing, I can speak to the Canadian data, as I was working on a national donor milk strategy. So-called "extended" breastfeeding (>12 months) skews almost entirely toward university-educated mothers as recently as 2010. The formula culture is so aggressive that, I believe, mothers have to be vehemently pro-breastfeeding to be inoculated against its messaging. DS2 is still heavily breastfed. I can see him nursing to 3 or 4 quite happily and wouldn't stop him if that's the path he chooses.
Re: HK's knowing more than the diagnostician, BTDT. I recall a debate with DS' paediatrician about co-sleeping in which I proved why the assumptions behind the supporting literature she cited were logically invalid and didn't prove what she was attempting to prove. We've had a few of those discussions, but they only happen once per topic, if you catch my drift.
