I am 59 my huband is 59 my son is 56 and he is 12 years old tall he's going to be at 18?

Answer 1

Unknown.

First, the final height to which someone grows is not based solely on the height of their parents.

Second, it is not known what stage of growth one is at when they reach the age 18. There is no way of knowing if they will continue to grow.