Adulthood and childhood are categories of future and past. Your challenge is exactly equivalent to saying, “If the past can affect the future, why can’t the future affect the past?”
The principle, enunciated by Lucretius, that “that cannot be touched which cannot be touched itself”, is sound insofar as it refers to objects conceived as persisting in time. “Adulthood” and “childhood” are not in this category. The closest correct version of your implied principle would be, “If the parent can affect the child, the child can affect the parent.”
Cf. “Dr. Diagoras” by Stanislav Lem
Yikes. s/b "that cannot touch which may not be touched itself."
You guys probably have much more knowledge on this subject than I, but it seems to be a valid analogy from my perspective.
Thanks for the input.