Recently, both Whoopi Goldberg and Jamie Foxx have defended Michael Vick's involvement in dogfighting by calling it a "cultural thing." What they're saying is, "Everyone else does it, so what do you expect him to do?" Usually our parents respond to that argument by saying, "If everyone jumped off a bridge, would you do it too?" While not grammatically correct, it's still effective.
Sometimes our cultures do stupid things out of tradition or ignorance. For example, there are cultures in Africa where female circumcision is the norm. Just because it's part of their culture doesn't mean that it isn't cruel, inhumane and wrong. Or how about the Nazi culture? Do we excuse the killing of millions of Jewish people by saying it was just part of the Nazi culture? As intelligent human beings we have the responsibility to think rationally about the traditions and rituals of our culture and reject the ones that are harmful or outdated. It's called progress. It's something the human race has done very little of, it seems.