Your dad is quite poorly informed, then.

"[Chickens] are, in fact, anything but dumb.

They can count, show some level of self-awareness, and even manipulate one another by Machiavellian means. In fact, chickens are so smart that even a limited amount of exposure to the living birds can crush longstanding preconceptions." https://www.bbc.com/earth/story/20170110-despite-what-you-might-think-chickens-are-not-stupid

"I have identified a wide range of scientifically documented examples of complex cognitive, emotional, communicative, and social behavior in domestic chickens which should be the focus of further study. These capacities are, compellingly, similar to what we see in other animals regarded as highly intelligent." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5306232/#:~:text=Chickens%20are%20misperceived%20as%20lacking,other%20animals%20(Eddy%20et%20al.