Answer i dont really know thats a very good question
Because children start out with the brain and the cells that they initially had. One thing that does not change is the personality you have a personality from the day you are born. The personality is the way you are when you are born and cells create your body and your mind. This is stable because it is like your chromosomes predetermined and does not change.
Hope this helps!
Answer: The first one, to keep the blood flowing in only one direction
