The Brains of Children

My mom and dad have been divorced for a while now, both remarried as well. Try explaining that concept to a four year old! My dad and his mom came over on the fourth to visit, and Lily started in on her research of the family tree.
"Papa Punkin, is that your mom?"
"Yeah, she is."
"Taryn, is this your dad?"
"Yeah." Thinking.....
"Taryn, is Mimi your mom?"
"Yeah." Still thinking........
"Papa Punkin, are you Mimi's best friend?" I can just see the wheels in her head turning....
"Well, she used to be."
Oh my, Lily is really confused! But she didn't say anything else about it.
He-child is always losing his cup. And I frequently get tired of looking for it. The following is a common conversation we have:
"Mama! Un koolade!"
"Where's your cup?"
"Where is?"
"Go find it and I'll get you something to drink."
"Un koolade!"
"Okay, go find your cup."
"Where is?"
"I don't know, I don't drink out of it. Go find it."
"Aww man...." Walks out of the room, head down and bottom lip out.
A few seconds later.....
"Mama! Un find it!"
"You can't find it?"
"No!"
"I don't think you looked for it."
"Eah I did!"
"C'mere, let's look for it."
Walk out of the room, and stumble over the cup.
"Look Caleb, what's that?"
"You find it! Un koolade mom!"
How many years until pre-k?