While science studies many things about memory, this is not one of them. Science can tell us all about the life of an individual, from conception to death. After death science can only tell us about decomposition(which is cool, but not your question).

Reincarnation, the idea that the soul continues into another life, involves supernatural ideas which science can’t study. The idea of existence after death has intrigued countless people, whether they believe in reincarnation, heaven, or some other afterlife. Other studies like religion, philosophy, and art explore these ideas. That’s a good thing. The world is much more exciting when there are many ways to understand it.

You may want to talk to your family about what they believe happens after death and how they came to believe it. What influences your thinking about what happens when we die?

So far as we know scientifically, people do not live multiple lives. This would imply that those people who claim to remember past lives are either dreaming about something that never happened, hallucinating, or simply lying. This could be overturned of course should evidence of a soul or something like that be discovered, but so far all such evidence is ambiguous at best.

That subject is outside of Science. There is no scientific concept behind it, but there are things Science doesn't know. There have been a lot of people who faked stuff about previous lives. Even in our own minds, it's hard to know if we are imagining things or not. But it's interesting to think about.