The genes would then be passed down to descendants in this switched-off state. Thus, the toxins that people ingest may not be the only relevant factor should cancer strike; the toxins that their parents or grandparents ingested could also be to blame.
比如，吸烟可能导致祖父辈DNA的发育遗传变化，关闭某些抗癌基因。这些基因将以关闭状态传给子孙后代。因此，人们摄取的毒素可能并不是罹患癌症的唯一相关因素，父辈和祖父辈所摄取的毒素也是罪魁。