Should Kittens Grow Into Cats?

I like cats that are good hunters.  I have some, and our neighborhood is full of them, so the hay-pile tarp remains free of mice and moles. But next door the female Manx (cats without tails) had kittens, and among them was a calico female.  Female Manx are excellent hunters and so are calicos so I saw no reason not to add another good hunter to the neighborhood.  Besides that, my grand daughter would be thrilled with a new kitten.
When we brought the little thing home, I sat in the living room admiring the eight ounce ball of yellow, black, and white fluff as she jumped and pounced on nothing in particular. I saw her hunting potential and I knew that as she grew shed' be just the hunter I had hoped for. At the same time, my little grand daughter visited us, carried her around the neighborhood all day, thrilled, as I had imagined, with her new baby kitten.
Two weeks later my grand daughter visited again . She leaped out of the car and ran for the kitten who was playing in the yard.  Then she ran to me with the kitten in her arms, fighting back tears. Wailing with desperation in her voice she said, "Grandpa, my kitten grew!" 
She somehow thought her gift of a baby kitten would remain as she first laid eyes on it.  I saw the kitten hunting as a grown cat.  And the kitten? It would probably grow as kittens do and turn into the cat it wanted to be without advice from either of us.
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