While "what is normal" is a reasonable question, a normal development is certainly closer to something that allows folks to achieve most things in any career/hobby/pursuit they choose.
Do you really see that as a "norm" being met by a majority of the population today? I don't think most people's lived experience is anything like that.
Normal being closer to what I said than what is usually achievable for folks with extra chromosomes? Yes, I do. I didn’t say it _was_ that anyone can achieve anything.
Normal development starts with having the normal number of chromosomes. I would think this is elementary biology.
I think of it as more of a probability question. There is a much greater chance of a person having two copies of chromosome 21 instead of three. "Normal" often carries some form of judgement but I guess technically you are correct to use the word.
No. Having two copies of each chromosome is NORMAL. Having 3 is NOT normal. Being completely unwilling to make normative statements seems rather cowardly.
Such that doesn't see you infertile and dead by 30.
Life expectancy is 58 "in the 2010s" [1], which is over 19 lower than average life expectancy in the same time period. Two decades isn't exactly insignificant.