prolonged drinking of breast milk leads to higher IQ
Statistics fail
There has never been, and likely will never be, a well designed experiment on the subject. You can stage an observational study, and that can lead to the conclusion that drinking breast milk and high IQ's are correlated. However, correlation does not imply causation, causation can only be determined by a well designed controlled experiment.
Saying that drinking breast milk leads to higher IQ is completely ignoring the very real possibility of confounding factors.