Do teachers ignore less attractive students?

A May 3rd article in the NY Times described a Canadian research study that found that parents took better care of their pretty children than they did of their ugly children. This was totally appalling to me, but made me actually think about from the perspective of teachers, as well, and whether they take better care of their attractive students. In my somewhat advanced age, I am not a "cute young thing" so I have noticed that those who are use it to their advantage and the teachers play right along, thus setting the stage for another study: Do teachers pay more attention to their attractive students? I hope I have not done this. I know I will pay more attention to my own actions as a teacher and make sure to give all students equal attention.