It's a good practice to have a parent class with private methods that are only used by their descendents?

Question

I'm trying to follow the SOLID concepts and at same time be DRY (not to repeat myself).

I have a parent class that is sharing a method between its subclasses, but this method is not used in the parent class itself:

class ParentClass
  def locals
    { id: ..., result: ... }
  end
  ...
  private

  def method_used_in_descendants  # this method is not used in ParentClass
  end
end

class ChildClass < ParentClass
  def locals
    super.merge { whatever: method_used_in_descendants, one_result: ... }
  end
  ...
end

class AnotherChildClass < ParentClass
  def locals
    super.merge { whatever: method_used_in_descendants, another_result: ... }
  end
  ...
end

# And not all the descendants of ParentClass need method_used_in_descendants:
class AnotherChildClass < ParentClass
  def locals
    super.merge { whatever: my_private_method }
  end
  ...
end

Is this method method_used_in_descendants created in the ParentClass a bad practice?

Thanks