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[Gremlins] Why are Gizmo’s “offspring” bad when he was not?

The first water droplets turn out crazy, hyper, cruel, and sadistic mogwai. The one that the science prof pops is much the same. Later when Stripe jumps into the pool, his offspring are not switched back to being good.
gpt
We see 7 Mogwai in the first movie (I just watched it again tonight).  Gizmo, Stripe, the other 4 at Billy's house, and the one given to the science teacher.

Gizmo is nice.  Stripe is mean.  The other 5 just seem to go with the flow.  When they're around Stripe, they're willing to follow his lead.  But when Billy takes one to the teacher, it's pretty well behaved (he doesn't say if that one is Gizmo or not).  It even says "uh oh" when Billy holds a water droplet over it.  Then when the other Mogwai grows, the two play with each other by tapping on the wall of the box.  Science teacher's Mogwai seems pretty nice as well, until he pokes it with a needle and draws blood.

I'd say that young Mogwai tend to follow strong personalities.  Left on their own, most will probably be fairly nice.  Maybe give them some time to grow older, and they will be like Gizmo.  But put a young Mogwai with a mean one, and it'll just do as the mean one does.