My feeling is it is a bit of both nature/nurture. I do feel you can influence. Some years back on university holidays I did door-to-door sales for ~6 weeks. I noticed at the end I was getting involved in all these conversations with people I wouldn't normally in day-today life. E.g. I'd order a beer at some bar and find myself having chats with the bartender, and genuine we're being friends chats. Something I've never been naturally inclined to do before. It was a fairly positive effect. That said I think it can go the other way as I saw a friend who moved into real estate sales becoming quite sleazy from I'm guessing being surrounded by that say what you need to make a sale culture for a couple years.