The 'it's all in how you raise them' mantra can land you in a lot of hot water. Dogs, like people, are a product of both their environment and their genetics. It is foolish to discount genetics altogether in the equation.
I have a lot of dogs through my house, many come from less then 'ideal' pasts, some from neglect cases, some from fight busts, etc. The range of INDIVIDUAL temperaments run the gamut, but the dog who has to be monitored the most, who can only ever be with my other dog under heavily managed situations, is the dog I have had since she was 8 weeks old. Heavily socialized, she's still just a B, and dangerous to other dogs. It's who she IS.