Dear Ilian, I understand what you meant, and I partially agree with you: captivity can influnce living creatures behaviour.
But, and this is an important difference, the lower you go in the complexity of the living creature, the less meaningful becomes the influence of captivity in behaviour.
A human being suffers a lot from being kept in captivity; a bear too and you cannot make 'reliable observations' (or at least observations applicable also in a wild situation) watching a bear in captivity...
But for a snake (if well kept in captivity) this factor is not so important. And I'm sure you will agree with me if I write that for a paramecium the distinction between "wild" and "in captivity" is virtually not existing: a paramecium will behave exactly the same in the water of a swamp as in the water of your personal laboratory...
Many years ago, I saw some Gonyosoma oxycephala specimens in the reptilarium of Zurich: the terrarium was so well made that seemed to be a real tropical rain forest, and the snakes were lying among branches and foliage in the same manner as you can find them in the Khao Yai National Park in Thailand.
Maybe subtle differences were anyway present.... probably the Gonyosoma of Zurich were more used to be handled by humans... but certainly their situation and well-being was very near to the one of wild specimens and surely not comparable with the one of a captive bear, or elephant or hippopotamus!
I hope my point of view is better explained now...
And, I repeat, the main difference between captive bred and wild snakes is, normally, the fact that captive snakes are less "shy" and less "aggressive" towards humans... I cannot really see other big differences, and I've kept snakes in captivity for years...