This is an old argument and there is a consensus too that wet and dry capping is a genetical trait. It is based on the fact that there are strains of bees that produce only one type of capping. And mixed type of capping produced by crossbreds working together sits well with this idea:
But then, those who are sceptical about genetical explanation are asking a very reasonable question. If this is a genetical trait, how the heck did this happen?
Same frame - two sides.
There is also an interesting experiment described by Vasilyeva and Halifman in their book Bees. There were two strains of bees involved. Caucasian that produces wet capping and Middle Russian which uses dry capping. Freshly built frame was given to Caucasian colony to fill it with eggs. On day three frame was moved to Middle Russian colony and brood was fed by them until it was capped. After that frame was put into incubator to exclude further influence of the foster colony. Enough frames were produced by this method to create a viable colony. After that, a frame of capped honey was taken from Caucasian colony (wet capping), caps were removed from a part of the frame and it was given to the new colony to repair removed caps. Result: Caucasian bees fed by Middle Russians consistently used dry caps to repair honey frames.
So-o-o… I hope you are still confused about the reasons behind wet/dry capping as I am