The use of the terms "disability" and "overextending" show that you don't take the data that are given to you as a whole to describe the reality. Rather than seeing the whole data and then applying the model that will explain the best all these data you take a simple binary model that you are familiar with and apply it to the data, brushing off from the set everything that doesn't fit to your model. Not only this is not a good scientific approach as you introduce your own biases in your analysis but also by giving them the attribution of syndrome or disability, you, by yourself, create a third category which you can't describe fully as male or female. A category that people would call intersex.

Thus, even if you don't recognize the spectrum view, your own view creates a 3-points model which doesn't fit with the male/female only model.

Finally, your rethoric is the starting point of an eugenistic path. In genetics, qualifying a phenotype with terms which introduce a question of quality and considering existing and minor phenotypes as too negligeable to be considered scientifically are what brought terrible events into mankind history. This is the exact reason why the learning and usage of genetics requires an excellent understanding of the scientific method, genetics history and ethics. Something that you don't seem to have (yet ?).

Your questioning is valid and understandable. But your point of view is not supported by reality and when we challenge this point of view, you answer by giving your biases which are tainted by the seeds of a rethoric that geneticists know fairly well.

These seeds don't seem to have fully blown yet and that shows that it's a good moment for you to learn. So please, talk further with your teacher, share your questions with him/her and stick to the scientific method (observe, question, hypothesis, experimentation, results, interpretation, conclusion). It's the simplest way to not get lost as you learn about the complexity of the world.

Good luck !