Why are..........?

I don't think this is always the case, in fact I usually see Asians portrayed as genius types, like the guy that plays the psychologist on Special Victims Unit. How about George Takei as Mr. Sulu in all the Star Trek movies. The there Sandra OH on the medical series, Julie Chen who does news and hosts Big Brother(although I don't now if this shows intelligence). I'm sure there are a lot more out there but I don't have much time to watch TV .