Modern day Londoners' grandparents have all heard about the offal and excrement floating in the Thames while toddlers sitting on the knees of their grandparents

Modern day Londoners' grandparents have all heard about the offal and excrement floating in the Thames while toddlers sitting on the knees of their grandparents, who heard about the same sitting on the knees of their grandparents. Hard to break a chain like that even with scientific evidence.