Is there such a thing as past lives? Is there such a saying that sins committed in previous lives will be punished in this life?

Of course, the essential relationship between parents and children is the karmic relationship in the past. Those who owed you in the past (not only money but also affection, etc.) will be unconsciously returned to you (that is, parents' debt). If you owed them in the past, you will unconsciously ask for it (that is, parents' debt). Good relations are mutually beneficial in the past, while bad relations are mutually harmful in the past.

Improvement methods are more mutual benefit, more good deeds, more repentance and elimination of old karma.