Task: Question Answering
Input (English): Context: He already seemed bigger and more intelligent , for example when you ask a question he 's gone from copying what you say , to automatically saying yes or no , and now is at the stage where he actually thinks before he answers and replies with more thought . You can actually see his brain ticking , its so cute . He was extremely excited to see us again and ran up to give me a huge hug . I was picking him up and doing weight lifting with him haha . 
Question: What may be the reason for his reaction ?
Output (English): He is my brother .