Every cell in your body (except mature red blood cells) – there are about 50 trillion in an adult – contains copies of your DNA, which are coiled up tightly to form 46 separate bundles called chromosomes. These chromosomes are stored in the core of the cell (nucleus), and there are 22 matching pairs, one of each pair from each of your biological parents, plus an X-chromosome from your mother and either an X- or Y-chromosome from your father;
一个成人体内有50万亿细胞，你身体中的每一个细胞（除了成熟的红血球）都包含着你的DNA数据。DNA分子紧密地盘旋而上组成了46条染色体。这些染色体存储在细胞的中央（细胞核），配成22对染色体。 每对分别来自你的生身父母双方，由你母亲提供一条X染色体，父亲提供一条X或者Y染色体。XX是女孩，XY则是男孩。