Gender Bias and Kids' Clothing

In theory, I'm against assigning strong gender roles to young children. In practice, I am pleased to have an infant girl that I can dress in cute dresses and things with bows, flowers, etc.

So, I was surprised when I went to the park with my baby girl (at just about two weeks old) dressed in what I assumed was unambiguously a girl's outfit (a cute outfit that included a bow on her light green shirt and white and green flowers on the pants), and an older lady said, "He's so cute!" She could not be convinced that this was a girl baby, despite my attempts to work "she" into the conversation. Apparently, if the clothes aren't pink or purple, it must be a boy baby.