Well, it might not matter how much is nature and how much is nurture, because Mr. Bennet tends to form his opinion of people pretty quickly. If William Collins showed up at 10 behaving rather stupidly, and never gave much evidence of actual quickness of intellect thereafter, I think Suzanne is right that Mr. Bennet would probably keep his distance. He might have some interaction with him, but it would probably be fairly minimal.
I don't think it's fair, though, to characterize Mr. Bennet as someone whose main amusement is in vexing his wife. He clearly derives most of his joy in life from his books and his two eldest daughters, with whom he has a close (maybe even unusually close, for the period? Lizzy seems to feel that he's been uncommonly kind to her) relationship. His treatment of his wife is undoubtedly unkind, but her treatment of him is not particularly pleasant either. She's always whining, fussing, bustling, demanding his attention, fretting, asking for more money. Spending time with her seems more like spending time with a demanding and possibly spoilt child than life with an adult, and I can only imagine how exhausting life with a demanding child that never grows up would be. Now that doesn't excuse his behavior. He certainly ought not to egg her on, especially in front of their children. But it would be exhausting, and I could forgive him occasional bursts of sarcasm if he were trying to do his best, and to look after his children's interests. He isn't, and I see that, rather than his teasing or vexing of her, as his real fault.
I don't think it's fair, though, to characterize Mr. Bennet as someone whose main amusement is in vexing his wife. He clearly derives most of his joy in life from his books and his two eldest daughters, with whom he has a close (maybe even unusually close, for the period? Lizzy seems to feel that he's been uncommonly kind to her) relationship. His treatment of his wife is undoubtedly unkind, but her treatment of him is not particularly pleasant either. She's always whining, fussing, bustling, demanding his attention, fretting, asking for more money. Spending time with her seems more like spending time with a demanding and possibly spoilt child than life with an adult, and I can only imagine how exhausting life with a demanding child that never grows up would be. Now that doesn't excuse his behavior. He certainly ought not to egg her on, especially in front of their children. But it would be exhausting, and I could forgive him occasional bursts of sarcasm if he were trying to do his best, and to look after his children's interests. He isn't, and I see that, rather than his teasing or vexing of her, as his real fault.