Sentence 1: I have a younger brother. 
 Sentence 3: Sometimes we would get in real fights and I always won 
 Sentence 4:  But one year, my brother had grown taller than me 
 Sentence 5:  I was quite surprised when he won the fight I started with him 
 Option 1: When we were kids we never had any fights. 
 Option 2: When we were kids I used to like to beat him up.