Yes.
GH is a endogenous hormone responsible for growth including your height, however the hormone transcript what is written in your genetic code. Unless you have some disturbance like gigantism.
And also yes, GH is used for stimulate growth in children. It should be applied at the right age, when you are in the growth phase.
If you are a adult, no, you are not going to be taller... the moment of growth has passed.
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