[minitel]

They probably, rightly, assumed that certain personality types gravitate toward programming work. They also probably felt that their manner and choice in clothing style helped to convey their personality type. For example, in their minds a programmer might choose to dress more like the girl in "The Girl With The Dragon Tattoo" or interact socially in a way that's either more intense (excitable nerd stereotype) or more withdrawn (shy nerd stereotype) than is the norm.

I know that despite my gender people will change their expectations about my career based on how I dress. When I had an undercut and wore around hoodies more often people were much more likely to assume I was technical. Now that I've gotten a little older and my fashion sense has become more conservative people tend to assume I'm a manager or in some other sort of administrative/people oriented role.

It doesn't take much experience in the world to notice that personality type, fashion sense, and career choice are correlated with one another.

It takes a lot of experience on the other hand to learn that you are supposed to ignore such things for the sake of politeness.