Yes, even gender. Gender is just another subjectively chosen category, which points to objective reality. In this case, it points to internal brain states, instead of sex chromosomes. It's like the word "Belieber". That's a category which refers to self-described fans of Justin Bieber. There is nothing factually incorrect with such a categorization. In fact, categories themselves logically can't be factually incorrect. It's only the faulty application of an existing category that can be factually incorrect. Categories can have fuzzy borders, but that's often just the nature of words whose definition emerges from conversation and common consensus.

> So for you Hindus were wrong

Hindus were also right -- in their local context where the word "gender" is defined that particular way. There is no globally right or wrong way to define the word "gender", because "gender" is just a word whose definition is decided by local common consensus, just like any other word in a language.

Different societies have different words for common greetings with slightly different implications on meaning. None of them are right or wrong because these words are simply containers that can hold whatever we want them to hold. And it's up to common consensus to put stuff into those containers.