Whole Sort Of Genl Mish Mash
1. If the consequence is not consistent,do people still expect a consequence?
If the desired consequence is inconsistent, then I would expect to see less frequent behavior (since the behavior isn't being reinforced). Depending on the reinforcement history, a certain consequence might be expected. As you know, sometimes we experience a consequence that doesn't comport with our expectations.
In the context of this post, if one expects more gifts if he/she gives more gifts - and then subsequently receive no gifts - one would expect their giving to be curtailed. At any rate, as the impetus for giving (whatever that might be) decreases in strength, then the giving will probably decrease in frequency.
2. Is the expectation a nature or a trained behavior? (by you given examples).
It can be either. At a very basic level, I think it is part of our nature. We seem to be wired at a very young age to learn by operant conditioning. The capacity is certainly there, even in infants. As we get older, much or our behavior becomes more complex and our reinforcement more abstract, but the basic mechanism (antecedant, behavior, reinforcement) remains pretty much intact.
3. Is it true that human naturally EXPECT a consequences to any given action? (Sir Ron, do you have good examples to support this statement?)
If, by "naturally," you mean whether it is connected with our biology, I'd say it certainly is. If nothing else, our ability to connect our behavioral responses to rewards or punishers seems to be part of our biological make-up. Without the biological capability to make such connections, we wouldn't be able to learn anything. More complex organisms come to expect reinforcement for behavior (as babies, food or a changed diaper for crying or, as adults, a paycheck for working). Culture also influences behavior (e.g., giving gifts on December 25).