I see this kind of response a lot, and unfortunately it's difficult to respond to you without taking what I feel you would interpret as a patronizing tone.

If you read the article, you would find links to research articles and additional literature related to the topic at hand. If you were in turn to read each of those articles, you would find that they are thoroughly researched and contain a large number of citations themselves. If you truly did not understand that you can educate yourself about a topic in this manner, I hope you are ecstatic upon learning to follow this great chain of research, as this is how every scientist educates themselves.

So, here's a link to the article that we are all discussing, go ahead and read it if you haven't already:

https://www.npr.org/sections/goatsandsoda/2018/10/25/6601918...

Here are some sources linked in the article. Some are peer-reviewed research articles, while others describe and cite peer-reviewed research:

https://bmjopen.bmj.com/content/8/9/e021616?int_source=trend...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768154/

https://www.unicef.org/publications/index_101397.html

Now here's the key insight into this process of learning--if you read the articles linked above, you will find citations of additional research in this area. These publications are usually not too difficult to find. Here are a few pertinent publications, but there are many more cited in the publications linked above--which I remind you were themselves linked from the original NPR article that we are all discussing.

Gershoff ET. Corporal punishment by parents and associated child behaviors and experiences: A meta-analytic and theoretical review. Psychological Bulletin. 2002;128:539–579.

Gershoff ET. More harm than good: A summary of scientific research on the intended and unintended effects of corporal punishment on children. Law and Contemporary Problems. 2010;73:33–58.

Sheehan MJ, Watson MW. Reciprocal influences between maternal discipline techniques and aggression in children and adolescents. Aggressive Behavior. 2008;34:245–255. doi:10.1002/ab.20241.

Hoffman ML. Affective and cognitive processes in moral internalization. In: Higgins ET, Ruble DN, Hartup WW, editors. Social cognition and social development. Cambridge University Press; New York: 1983. pp. 236–274.

Eron LD, Walder LO, Lefkowitz MM. Learning of aggression in children. Little, Brown, & Co.; Boston: 1971.

Durrant J, Trocmé N, Fallon B, Milne C, Black T, Knoke D. CECW Information Sheet #41E. University of Toronto, Faculty of Social Work; Toronto, ON: 2006. Punitive violence against children in Canada. Retrieved from www.cecw-cepb.ca/DocsEng/PunitiveViolence41E.pdf.

Obviously this is just a tiny selection based on a few minutes of research (which I remind you you could have easily done yourself!)

Now, I leave you with a question: did you really not know how to do this yourself, or were you trying to imply that because this "long line of research" was not handed to you on a silver platter it does not exist? Am I right in thinking that you might also be a little pleased that I wasted my time educating you when you transparently have no interest in being educated?

To conclude, I can't read for you, I can't learn for you, I can't think for you (and I don't mean thinking of clever little rhetorical gotchas, I mean real thinking with the aim of comprehending truth and reality), and unless you have at least attempted to read and learn and think for yourself, you have no foot to stand on when you argue against research that you (for some reason) disagree with.