There could be differences in the physics of cell division, this process of separating into two cells such that even though they both have the same chromosomes, they both have the same DNA content, maybe one of the cells entraps something that's different than the other cells.

细胞分裂的过程中的确可能会产生差异,在分裂为两个细胞的过程中,尽管两个子细胞含有相同的染色体,含有相同的DNA组成,但也许其中一个细胞,截留了和其他细胞不同的物质

耶鲁公开课 - 生物医学工程探索课程节选