Hate to answer for someone else, but there is a significant difference between being 'realistic about' and 'arguing against'. @chickentrains is simply expressing objective knowledge.
As with almost anything, it's a combination of genetics and environment. We spent some time competing in obedience trials at UKC events with golden retrievers. Generally these were dual events conformation and performance. Pitbulls are UKC recognized and were a large part of the conformation...