The movie was too vague on the particulars of how the Caminans were conned into brainwashing them in this way and by what method. There is nothing in episodes 2&3 that contradict biochips, and that method actually makes sense. Total slaves, such as the ancient Sith Alchemists engineered, were exactly the kind of slaves you assume the clones to be, but a hive mind like that would have stood out to the Jedi, and made the clones very creepy. Before he was recruited to become a Sith, Palpatine, like Padme, was eugenically bred to be a super politician by Millennia of their world’s efforts (which may have been a major reason his master picked him) and that inherent Savvy, made him understand that it was vital not to become too scary too soon. Allowing the Clones a degree of genuine humanity made them easier for the Republic to accept and eventually depend on them. Of, course, that carried a risk of anomalies like Tuup and Fives, but he probably calculated that such was bound to happen from one in a million, and therefore an acceptable risk that could be dealt with.