Although there is no definitive answer to this question, there are some general insights that can be shared based on expert opinions. It is generally accepted that children have shorter attention spans than adults and therefore may forget someone more quickly. Additionally, younger children are often more egocentric and therefore may not fully understand the concept of forgetting someone. Older children and teenagers may have a better understanding of the concept of forgetting but may still struggle with actually forgetting someone due to the emotional nature of memories. Ultimately, the length of time it takes for a child to forget someone will depend on individual factors such as age, development, and emotional attachment.