Reincarnation is opportunity.
As spiritual children of God, we were born in His image and likeness. We got distracted and fell into a dependency upon physical instrumentality (senses through physical means, only). God had to create Homo sapiens so that the otherwise dead asleep (catatonic) children would have some method for gaining continuity of consciousness.
Outside of physical bodies, we have only dreams, some of them nightmares. No ability to plan and execute a plan for escape from physical dependency. Lost souls!
Reincarnation isn't tied to a specific family, but this doesn't prevent one from being born again into the same lineage.
Some people remember because they are ready to remember -- because they have let go of the barriers to remembrance.
When a very bad man lives a life of murder, theft and lies, they care not for the feelings of others. They are living only for the self -- ego.
How can such a person ever be saved from physical reality? The only thing most people take with them in death are the wages of their lives -- the "fruits" of their labors -- karma -- what Jesus described as dying by the sword by which one had lived. Numbers 14:18 described it as the sins of the fathers visited upon the children of the 3rd or 4th generation. Reincarnation. When that evil person dies, they are born again and grow up to an age where they can appreciate the boomerang which they themselves had thrown, 3-4 generations earlier. If they can be made to ask, "Why, God, is this happening to me?" the door is suddenly open to their heart. Humility can finally be theirs. The once arrogant murderer has finally softened their heart for learning.
Reincarnation is multiple opportunities for learning and for re-awakening as a spiritual child of God. And that's what all of this is about.