Hello Larry ... Your question affirms my point that once an observer has a category (e.g. "male") in mind, there are almost automatic limitations on the following observations. Two thoughts come to mind.  The first is that the physical distinctions are not always that easy to identify (hermaphrodites, for example). The second is that regardless of the physical "category" there are the psychological identifications (of the one being observed). Transgender people almost always describe that they knew this "psychological truth" early in life.

As scientific knowledge progresses very likely the categories become more "fine-tuned" - hopefully gradually closing in on what is "more true" of reality than was previously understood. The mores and laws of any social group/government always lag behind what is actually happening in a population. I would love to know what the laws of the US will be in 200 years. I bet people will think that some of our 2016 laws were strange and archaic.