Personal Narrative: Twin Primes

"Isn't this great?" my dad asked excitedly. "It's the last night you and your sister will be twin prime ages until you're 11 and she's 13--six more years!"
I was trying to sleep, but my dad dragged me back to the world of the living.
"Sam, can you tell me how many times you two will be twin primes before you turn 21?" Dad was tempting me. He knew I wanted to go to bed, but the urge to be right and earn his smile was too great.
In my mind I made a number line and crossed off every even number, then the odds divisible by three, five, seven and nine (except themselves), and, of course, one. Looking for twin primes, I located 17 and 19, 11 and 13, as well the triplet three, five and seven, which I divided into two twin primes.
"Four," I stated confidently.
Ouch! I'm sorry. Would you like to try again?"
Scrambling for a paper and pen, I frantically checked my work. No, there were definitely four twin primes.
He glanced at my paper. "Did you include my favorite prime?" Dad asked with a sly smile. As a puzzled look crossed my face, he answered his own question: "You didn't include two."
"I know," I responded slowly. "It's not prime; it's