Fun fact, the second X chromosome is just a sitting duck. Once a body develops the first one, unless a Y chromosome is also in order, the body has already completed the parts of the blueprint it needs to live a long and stable life. This is where Turner Syndrome, a form of Down Syndrome or intersexuality where someone has only one X chromosome and no Y chromosome or second X chromosome, comes from, and people with Turner Syndrome can live their whole lives not knowing they have it (the opposite is actually true with the Y chromosome, where if you only have Y chromosomes and no X chromosomes, you die in stillbirth).
Fun fact, the second X chromosome is just a sitting duck. Once a body develops the first one, unless a Y chromosome is also in order, the body has already completed the parts of the blueprint it needs to live a long and stable life. This is where Turner Syndrome, a form of Down Syndrome or intersexuality where someone has only one X chromosome and no Y chromosome or second X chromosome, comes from, and people with Turner Syndrome can live their whole lives not knowing they have it (the opposite is actually true with the Y chromosome, where if you only have Y chromosomes and no X chromosomes, you die in stillbirth).