Instinct and a sheer will to survive. Humans are known to react instinctively to certain situations. Fortunately for most humans we have the intelligence to over ride a lot of what our instinct tells us to do. Lucky for snakes they don't have as much capacity to reason things through. All creatures on this earth our born with a certain amount of instinct. When you were first born did your mother have to teach you how to suck on a bottle or breast? No, this was something mother nature made sure you knew how to do as it is required for survival.

On the same note lets answer the question, would a captive hatched adult snake be as likely to survive as a wild hatched and raised snake if released bach into the wild? If you took a 10th generation captive bred/Captive hatched hatchling and released it would it have the same chances as a Wild hatched? Or at some point by each generation being given certain things does some of the natural instinct start to be left out of the genetic coding of the snake as mother nature is famous for the use it or loose it adaptations during evolutionary cycles? Granted most evolutionary cycles take thousands if not millions of years.