Nor does classic genetics explain how, despite their identical DNA sequences, monozygotic twins1 or cloned animals2 can have different phenotypes and different susceptibilities to a disease.

• 尽管DNA序列相同，单合子的双胞胎或者克隆的动物如何有不同的表现型和对同一疾病不同的易感性，经典的遗传学也不能解释。