I take it that the capability of the mentors, in this case the Jedi, is a factor of influence, isn't it? Most victims don't live as part of a religious order with strict behaviour codes, most victims aren't told they are "the chosen one" who's responsible for the fate of the whole Galaxy, most victims don't live and aren't relied upon as war heroes in a civil war, most victims also don't have visions of people close to them dying that have proven true, and above all, most victims don't have mentors like Palpatine. I'd like to know how many victims would be able to lead a normal life under circumstances like these. He wasn't "forced" by specific persons. If that means that he has a "free will" (a debated notion in general, in disciplines from neuroscience to philosophy) and was free to consciously choose as he wished, or if he was "forced" by psychological pressures stemming from his childhood is a different question, I think.