What we don't clear carries over to our children and their children. If you have skeletons in your closets, or family hot potatoes (secrets, dramatic events...) whatever you don't heal gets carried around and often amplified in future generations, burning the hands of each generation who gets to handle the hot mess, which no one even remembers. There are different methods for clearing the past especially if stuff is deep. It is often useful to try several as each digs into the problem from a different angle: psychoanalysis, trans generational therapy...
My approach is family oriented. We look at what has happened to previous generations and how it plays itself in our lives and we undo it through a series of rituals. It works even when the protagonists have passed away. We also identify which wounds (filters) have been passed onto us by our parents and by which we interpret the world: unfairness, abandonment, betrayal, you know when you and your siblings/spouse have totally different interpretations of a same event! I also work with our inner children and all our previous selves, who we might think are from 1980, 2000 or 2020 but are still alive and kicking!
Whether with me or with someone else, when you work on healing yourself, you are healing the future generations and everyone around you. You cool down that burning potato, bury it with dignity and move unto your real self, the life you are supposed to fulfill and you help your loved ones do the same. This is one way of being heliotropic which is very important to me (amazing book, must read for all btw, Be The Sun Not The Salt)!