The father is an alcoholic, but it uses the idea of walking straight to mean both literally, regarding his alcoholism, and figuratively, as in to state that he should, as a father, be walking a straight line, because his son is following him and "walking" as he does.
The father is an alcoholic, but it uses the idea of walking straight to mean both literally, regarding his alcoholism, and figuratively, as in to state that he should, as a father, be walking a straight line, because his son is following him and "walking" as he does.