Pretty? Well I'm alright. But, yes I have been told I can intimidate people and I have seen it when engaged in conversation.
Why? Well, I know I have a more domineering personality, very opinionated, and serious (a by-product of my educational background and work environment). So, I subconsciously bring that into my conversations.
I attempt ad nauseum to relax both body and mind when in conversation - I have found that beer helps.