Humans have fewer instincts than most other animals.
We have to learn practically all of the behavior patterns which allow us to survive, compete, cooperate, communicate, even procreate. Learned behavior is a function of its consequences, of the temporal relationship between what you do and what happens afterwards. You pick up a smoking log, you feel pain. Next time you stoop to pick up a burning log, you hesitate. You take a bite out of a strange fruit, and it tastes good and doesn't make you sick.