Rebirth, transfer of memories, what is it?

I have a person in my own family who's aware of his past-birth. He knew it by age 7 only. When family started investigation 'they found it all true. How he has died in his last birth, how much of children he had, what work he was doing when he died and etc. I want to know what the buddha said about rebirth and transfer of memories to a new born? Moreover I wish to get more examples.