The topic of free will is debated among philosophers. There is no proof that it does or doesn't exist.
I think that for a very high number of them the training would stick hard, and would insist, upon questioning, that they weren’t human. And have any number of justifications that were logically consistent for it.
Of course I can’t prove this theory because my IRB repeatedly denied it on thin grounds about ethics, even when I pointed out that I could easily mess up my own children with no experimenting completely by accident, and didn’t need their approval to do it. I know your objections— small sample size, and I agree, but I still have fingers crossed on the next additions to the family being twins.