3f) The reader's statement has a problem with reverse causation since it is based on a correlational study.
This statement is incorrect. While some correlational studies do have a PRAH of reverse causation, like the Freedson et al. weight lifters study, reverse causation does not apply to this study. Here it would mean that the amount of spanking causes parental age which is obviously impossible. PRAHs need to be identified by careful analysis, thinking through how it would work to see if it is plausible.