Extract from a Tablet of ‘Abdu’l‑Bahá
Thou hadst asked about the meaning of the statement “the transgressions of the parents will affect four generations of their descendants.” Know thou that spiritual diseases are like physical ones. Thou seest that if a person is afflicted with a chronic physical illness, traces of his ailment will linger in three or four generations of his offspring. Likewise, should he be afflicted with a spiritual disease, that of an immoral character, this will have a great influence on his progeny, for upbringing exerteth an astounding influence and that person’s character will be passed on to his descendants. A powerful force is thus needed to eliminate that influence. By this “transgression” is meant immorality and heedlessness of God. In truth, this transgression is the breaking of the Covenant, the abasement resulting from which will linger in the descendants for four generations.
And now, I hope that thou shalt become the cause of the illumination of souls, so that they may acquire a heavenly nature, and that thy goodly character may exert its influence upon a vast number of people.