A- Sigmund Freud first formulated the theory of “ infantile amnesia,” saying that we suppress memories of events that happened before the age of 3. Today, scientists believe our inability to remember our infant and toddler years has more to do with the brain’s neurological immaturity and the child’s undeveloped language skills. Recent studies suggest that memories start to form when a child’s ability to reason fully has developed, usually around the age of 4. At this age, children can use words to ‘file” away memories.