Why do Gorillas not attack you when you enter their habitat. Wouldn’t they want to protect their pack/family?

Question: Why do Gorillas not attack you when you enter their habitat. Wouldn't they want to protect their pack/family?
- Keywords:
  family,
  gorilla,
  protect,
  territory
Asked by tezzer to Charlotte, Jo, Kevin, Louise, Valeria on 18 Jun 2012.
- Joanna Cruden answered on 18 Jun 2012:
  
  Gorillas don’t have many predators and are pretty intelligent, providing we do not do anything which seems threatening to them or their family they won’t attack because they don’t see us as a threat, and let’s be honest if we don’t have a gun in our hands we are not much of a threat to a gorilla!

Question: Why do Gorillas not attack you when you enter their habitat. Wouldn't they want to protect their pack/family?