Poopie Head

I don't understand this whole sibling dynamic. My brother and I are 10 years apart, I am perfect he is not.  I was an only child until I was almost ten.  I loved my brother from the moment he arrived.  When I morphed into a tragic teenager, he was a sweet little boy.    My mother reminds me quite often that "she did it right!"   Lately, I have wondered if she did in fact do it  right.  The dynamics in my home leave me flabbergasted.  E and C argue about everything and anything.   This was the fight this morning at 6:30 am:
C: "Mommy! I went poop"
 E: "I went poop first."
C: "No I did!"
Me: "Who didn't flush the potty?"
C: "Not me, it was E"
E: "It was C, it looks like C's poop."
Me: "Really how do you know what Middle C's  poop looks like? "
 E: "She talks too much when she eats and doesn't chew her food, there were chunks. "

On a positive note, Middle C has been doing well in Kinder.  I had my concerns, but she has earned three super behavior stamps.  When she was chatting about her day, she mentioned that today's stamp was very light because she just barely earned it. She colored her hand black because she wanted to look like the little girl sitting next to her.