One must know that alcohol gradually penetrates the bone marrow and ruins the blood. By harming the offspring, all the descendants are thus harmed. If an alcoholic has three children, for example, these three are harmed only a little; their descendants, however, are significantly hurt. Alcohol has a long-term negative effect that manifests in many generations. Much of the weakness that exists in humanity today is simply due to ancestors who drank too much.
One must indeed picture it like this: here is a man and a woman, the man drinks too much, and the bodies of their descendants are weakened. Now think for a moment what this implies in a hundred, and worse, in several hundred years! It serves no purpose to examine only a decade, say from 1870 to 1880, and to conclude that more people died from water than from alcohol. Much longer periods of time must be considered.
Source: Rudolf Steiner – GA 348 – Health and Illness II: Lecture III: The Effects of Alcohol on Man – Dornach, January 8, 1923