If you check the 'skip fallout behaviour' box in someone's AI packages he won't initiate any conversations with anyone, or even greet them. And nobody will talk to him either. I don't know if there's any way to tone it down without eliminating it entirely.
Now where do I know your username from...
Edit: Oh right. The UMP and the Amazing, Wonderful and Spectacular (and slightly outdated
) texture pack comparison page!