Our sins affect other people, including our children and grandchildren or as Scripture says, “to the third and fourth generation.” We aren’t punished for our parent’s sins, but we have been affected by them. We suffer when other people sin.
The ancient House of Israel were so far gone, so utterly unrepentant that God’s only recourse was to send 90% of them to the grave and the other 10% into exile. The exile will end only when Messiah Yeshua returns to the earth.
The descendants of Israel, North and South, inherited the covenant of Abraham, Isaac and Jacob at Mt. Sinai hundreds of years before. Yet, instead of living in that covenant, the children of Israel preferred to imitate the practices of the nations around and actually surpassed the surrounding nations around in their iniquity. This is why God judges the entire family of Israel much more severely than He punishes the other nations. This is the prophet’s warning in Amos 3.