[The Diminishing and Corruption of the Children of Oppressors]

Answer – and Allah is the Protector who grants success: The belittling of the children of oppressors and their corruption is not a punishment or recompense for the oppression of their fathers. Rather, their corruption and their being belittled arose from the side of their upbringing, since they grew up between two corrupt parents and were brought up in their laps. For the upbringing of the parents has an effect on their child: if the parents are righteous, righteousness grows in the child; and if they are corrupt, corruption grows in him. Concerning this came the ḥadīth: “Every newborn is born upon the natural disposition (fiṭrah), until it is his parents who make him a Jew, or make him a Christian, or make him a Magian.” So the nature of the parents, their character, and their religion have an effect on their child: he takes on their natures, adopts their character traits, and follows their religion.
If it is said: The child who is raised in the lap of his corrupt parents may have an excuse before Allah, because his misguidance did not arise from his choice nor from anything on his part.
It is said in answer: Allah, exalted is He, has invalidated such an excuse by means of reason, and by means of the Messengers, may Allah’s blessings be upon them, and by what He sent down of clear proofs and evidences in His Books and upon the tongues of His Messengers.
And Allah, exalted is He, did not excuse those who said: “Indeed, we found our fathers upon a religion, and we are, in their footsteps, [rightly] guided.” [Az-Zukhruf:22]
If it is said: It has been narrated, the meaning of which is: “Whose flesh grows from illicit gain, then the Fire has more right to it,” and from this it is taken that eating what is unlawful has an effect on the misguidance of the children whom their father nourishes with the unlawful.
It is said in answer: What is meant by that is the morally responsible adults who nourish themselves with the unlawful, eating usury, bribes, and the wealth of people without right. Children are not included in that, because of what has come in the authentic ḥadīth: “The pen has been lifted from three: from the child until he reaches puberty…” and so on.
As for what has come regarding the child of fornication, the cause of his corruption is his growing up in the lap of the woman who committed fornication, and the cause of his corruption is not that he was created from unlawful semen.
Furthermore, even if we suppose that unlawful semen and unlawful wealth are two causes of the corruption of the child who was created from the semen of fornication, and of the corruption of the child who was nourished with unlawful wealth, that still does not reach the level at which there is no way of escape from it. For such a person, even if he has reached a far degree in corruption, is able – by his intellect, his hearing, and his sight – to know what is true and correct, and to distinguish between right guidance and corruption. He possesses freedom of choice just as the rest of the morally responsible do. And if the matter is thus, then the proof of Allah, exalted is He, stands against him.
If it is said: We see that people differ in their natures: among them, is he whose nature inclines toward evil, and among them is he whose nature inclines toward good; this becomes apparent in a person from his childhood, which indicates that this is an innate nature of creation, not a disposition acquired from the parents.
We say: The matter is approximately as you have said, but this does not conflict with moral responsibility (taklīf). It is within the capacity of every person to forbid his soul from its evil and to restrain it from wrongdoing; it is possible for the miser to force himself to be generous; it is possible for the liar to force himself to be truthful; it is possible for the treacherous person to force himself to be loyal; it is possible for the fornicator to force himself to be chaste; it is possible for the one who cuts off kinship ties to force himself to maintain ties and show filial piety, and so on. It is only that giving in charity is easy for the generous person and difficult for the miser, and so forth.

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.3