Um, that's a negatory good buddy. It's called a "plot point" and unless I missed it, Dexter didn't even know about the arm. They won't be going there, he is a psychological door Dexter opened at that moment, the moment he realized he has nothing but darkness for realz, just like his brother, and always will…

That boy is Hanks' son from another marriage.  And he does look like his mother more than his father.  She was an actress too though I cannot remember her name right now.  Don't know about the pineapple thing.  I must have missed that part when my kid was puking.