This is absolutely false. Using this as a determining factor in guessing the sex of a potential addition to your aviaries offers no better odds than flipping a coin.
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.