In today's inbound Andrew raises an interesting question, something we generally term Nature versus Nurture. It has been a hotly debated issue in past years, that of whether or not the type of person we become as adults is more influenced by the inherent natures with which we were born, or whether our life experniences do more to shape our personalities.
In the probes' case, I would definitely think that their experiences have had more to do with their differences precisely because they were all built to identical standards. Humans, on the other hand, are all inherently different at birth due to a variety of reasons, genetics being a prime example. With us it has to be a blend of the two forces of Nature and Nurture that shapes us as adults.
What is interesting to me is that even though the probes started out as identical units, as sentient creatures their varying experiences have allowed them to develop different personalities.
CZ