Infancy is generally believed to be the best period for indoctrination. Hence, in such countries as Russia, China, etc. Where indoctrination is carried on, it is introduced at the stage of infancy itself.
This applies even to religious indoctrination, not only to political indoctrination. In fact, indoctrination depends mainly upon the predominance of sentiment, not upon that of reason, and it is found that, generally, emotional individuals are more susceptible to indoctrination. This process achieves its highest success among individuals with a low intelligence quotient.