The concept of a generational curse comes from the second of God's holy Ten Commandments.
4. You shall not make for yourselves any graven image, or any likeness of anything that is in the heavens above, or that is in the earth beneath . . . 5. You shall not bow yourself 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 unto the third and fourth generation of those who hate Me, 6. But showing mercy to thousands of those who love Me and keep My commandments. (Exdosu 20:4 - 6, HBFV)
Some see such a "curse" as being caused by an evil spirit who has the power to harass the descendants of a particular person who is prone to commit certain sins. Still others see it as being a general "spiritual inheritance" in nature. Such curses are not thought to have a connection with heredity-based problems like a tendency to abuse alcohol.
Those who are under a generational curse, it is argued, are prone to committing certain types of sinful behavior. Solutions to this type of penalty include having someone involved in a deliverance ministry "discern" the exact curse a person possesses. With this information the individual can then specifically renounce the curses against them. If it is believed that the cause is an actual evil spirit, the deliverance ministry will try to "cast it out."