I agree with spanking completely, a child has to be given boundaries and they can not always just be told to a 4 year old, they need to be made clear. A parent teaches a young child values and what they believe is right and wrong. Once a child matures enough (soo that they respect others, ...etc etc) then that is when a choice should be given for them to decide in what they believe in. But spanking under some circumstances, to enforce strong boundaries of right and wrong is acceptable soo long as it does not become abuse.
I might only be fifteen but my parents I believe have done a pretty good job raising me, I was taught what was right and wrong, and to respect other cultures. But before long, grade 3-5 my parent's influence began to diminish, my friends and peers, became my main influence.
I was a relatively sheltered child and I was certainly bullied and picked on, but things changed when my parents got divorced, I became more exposed to the real world. I became aware of what was really happening in the world, I developed my own opinion in politics and religion, without much influence from parents that weren't there like they had been before.
Friends and peers will always have a certain advantage to influence over parents after a certain age. So in the end a parent can only teach their kids whats wrong and right, whether by force or words. A parent can shelter a kid through they're life but at some point, for better or worse a parent must let they're kid chose their path.