Birds have absolutely no ideas about human gender. Ignoring feathers, parrots have no external physiological features that they are keyed to in order to determine the sex of other parrots. Therefore, it would be logical to assume that they would not understand these differences in humans. What they are keyed into is the color and the shape of plumage. I'm sure that everyone is familiar with the human silhouettes that are painted on restroom doors.
Humans present themselves in two distinct forms with variation in between.
It is the individual bird's experience with these different forms that may lead to prejudice against one form or another. Parrots, just like people, are very individualistic when it comes to their propensity to acquire prejudice. Some will never show this tendency, yet others will form them with only the slightest motivation. If a parrot does not like how it has been treated by one form of human, it can adopt a lifelong distrust for all other humans of similar form. This is form recognition, not gender preference.