That all is true, but, dogs have been selectively bred for certain traits. No matter how much one would expose whippets to guarding sheep, very few would ever do so. You would have an outlier here and there that might. Same with herding.
I LOVE pitties. I think they are great dogs. One of the easiest breeds to come in for photos. The reality of it is they are more predisposed for dog aggression, to pretend they aren't is just as unfair as believing they are all man killers.
I have lived with one and she was a great dog, raised on a farm(went with me daily to the barn I worked at) around dogs non stop and she was still dog aggressive. She might not eat one, and then, she just might. Add in the fact she was an alpha bitch didn't help much.
I have a house full of very dominant dogs and never have a scuffle. Whippets were bred to be in a pack. YES, you will find some that aren't right in the head and some that can't be with other dogs but it is the rare one.
I have seen way too many bloodlines have the same personality traits, that there is way more nature to dogs than nurture. Same with people. Yes, they way they are exposed and raised makes a difference. The way they are to begin with is the majority of it though