Allison, I will toss in my 5 cents as a scientist. Not the best scientist, not the worst scientist, somewhere in the middle.
Normality does not exist, never had and never will. Normality is the byproduct of our desire to simplify the world and make sense out of it. When the decisions are about how to get out of the claws of the lions, find a partner whom to make babies with or where we are likely to find ripe berries, it works ok. That is what our brains evolved to achieve. When we apply our basic simplification inferential machinery to more complex problems our brains weren’t made to work with, we mostly say nonsense (in passing, that produces also racism, sexism and many other diseases of our society in my humble opinion).
Let me argue for it. People are very complex beings, we have many traits that define us. Let’s say there is one hundred of those for simplicity, reality is more complex, but I don’t believe that we need to be that complex. Let’s look at just one, let’s say height: more people in the middle, fewer people at the tails. Defining normal is easy, let’s say the central 90%, the top and bottom 5% are very short or very tall, ergo “weird.” Works well, except that being human has 100 dimensions in our example, not one. If we assume those traits to be reasonably unrelated to each other (taller people aren’t particularly kinder or smarter than short people as far as I know) let’s see what happens with two. If normal is center 90% for each, how many people are normal for both? After all we can’t make absolute statements of normality with existential implications that change with the problem we are dealing with! You need to multiply to get that number (I can write more about that if anyone is interested), and it is going to be 81%. What if we have 100 dimensions? Turns out that only 0.0027% of people (about 800 people in the US) would be normal. In the end to paraphrase a friend of mine: it is totally abnormal to be Normal! Normality is a useless category to assess humanity, for the most part.
So, their definition of normality is just based on looking at one thing and defining your humanity with it. They need to go back to school.
In passing defining human gender using just X and Y chromosomes in the sense of one or two each is a bit outdated as well as far as I know.
They are boring in their ignorance and superficiality.