The higher IQ of breastfed kids is probably from BOTH the milk and the parenting.
Edith White of Health Education Associates has an excellent self-study module on why BF increases intelligence. The research cited (and there is a LOT) gives arguments for why this is both psychosocial and because of the milk itself. It's well worth the money to get and read, IMHO - and you can earn CERPS too. Contact Health Education Associates, 8 Jan Sebastian Way # 13, Sandwich MA 02563 for information.
Linda Smith, Dayton OH