There seems to be a contradiction in the Bible regarding who bears the punishment for a sin. Obviously, no one else should be punished for a sin someone else commits, and the Bible agrees. God explicitly commands us not to punish even a child for the sins of their father. But doesn't God do just that? In Exodus 20:4-6, it certainly seems so, at least as far as idolatry is concerned.
The correct way to understand this verse is to distinguish between a collective judgement and a generational curse. Does God punish a sinner's children for their father's sin? Sure, IF they repeat their father's sin. Particularly, as the case is here, for the sin of idolatry. Tell me, if a man is a Muslim, what religion will his child be? It's not guaranteed, but that child will likely be Muslim, correct?
Now, let's look at the verse itself. I'm going to highlight one word: "“You shall not make for yourself a carved image—any likeness of anything that is in heaven above, or that is in the earth beneath, or that is in the water under the earth; you shall not bow down to them nor serve them. For I, the Lord your God, am a jealous God, visiting the iniquity of the fathers upon the children to the third and fourth generations of those who hate Me, but showing mercy to thousands, to those who love Me and keep My commandments."
So, how many children does it take to break a generational curse? One. If you're the second, third or fourth generation, does God punish you? Yes, IF your fathers sins become your sins. But what if they don't? What if your father hated God so much that he created a carved wolf and worshipped that wolf instead, but you repent of worshipping that wolf (or, by some miracle, never worship it at all), you love God and you keep His commandments? Well now you're not being punished for your father's sins anymore, because they aren't your sins (Ezekiel 18:14-20). Now, you're among those to whom God shows love, and He will do so for a thousand generations. That is, unless they, too, turn on Him.
This concept is actually shown in an entire Biblical book: Ruth. Ruth was not a Jew. She was a Moabite. And yet, because she forsook the idolatries of Moab, and instead repented and served the God of Israel, she was not only forgiven for her sins but ultimately became an ancestor of Jesus Himself.
The irony is that not even the father himself necessarily needs to be punished for his sin. Particularly post-crucifixion, you are free to repent and believe, and so even your vilest blasphemies can be placed on the cross of Christ, while you, rather than dying for your sin, actually inherit eternal life! How beautiful is that? God looks down on us, sees our idolatry and our sexual immorality and our greed and our violence, and yet He says "I love them. I take no pleasure in the death they deserve. And so I will give them the life that Jesus deserves."