The earliest age from which adults typically have memories is disputed. Psychologist Richard McNally has written that most adults cannot recollect anything from before the age of three or four but Karl Sabbagh found that many of his friends and acquaintances had memories from the age of two or before. Sabbagh suggests that the earliest memories tend to be be visual snapshots and that these lacked the narrative structure which other researchers required.
Charles Darwin's earliest memory was of a cow which startled him, causing an accident which left a scar. He placed this memory as being before the age of four and thought that the details were sufficiently clear that the memory was not a false one generated by family reminiscence.
New research, done by Harvard, now suggest that childhood memories can make a person more helpful and charitable. There's something about recalling memories that takes one back to their own youth, a time of moral purity and goodness, that makes a person's behavior more social. Whether the memory was good or bad, it sticks with the child and can carry over into their adult life.