"It all comes into effect on some small level, that's why my equations work so well. Something that happened then you were not even seven could cause you to make a subconscious decision that changes your path in life. Had Harry not met Ron at Kings Cross, Draco may have befriended him and both of them would have been sorted into Slytherin. Imagine what the world would be like instead, a half blood wizard forced to live under the staircase of his muggle Aunt and Uncle."