It starts while we're still in the womb. For example: A Philippine candy brand called Kopiko sent doctors candy to give away to pregnant mothers

What pregnant women eat not only affects their unborn child's development, but their future habits too. A pregnant mother's diet physically transforms the fetal brain, which affects what the baby will later want to eat, according to studies by Dr. Josephine Todrank at the University of Colorado School of Medicine.

But the case with Kopiko is extreme. Months later, it rolled out a coffee product which tasted just like the candy, which became hugely successful with kids. Lindstrom says that mothers would even give agitated newborn babies the coffee, which quickly calmed them down. Four years later, Kopiko coffee has become the third-largest brand in the Philippines.

Source: Brandwashed: Tricks Companies Use to Manipulate Our Minds and Persuade Us to Buy, by Martin Lindstrom