all other chromosomes in such diploid organisms are paired, but https://mahoraize.wpxblog.jp/%E8%AA%B2%E9%A1%8C%E3%83%BB%EF%BD%8E%EF%BD%8F%EF%BC%8E%EF%BC%96%EF%BC%93%EF%BC%8D%EF%BC%92/ organisms can inherit 1 either two X chromosomes.