If not by someone else, certainly by the circumstances of your birth which you did not chose. So, life is very much like a lottery and what we think of us as individuals is mostly shaped by what's around us.

It is a humbling view. But there can still be an authentic "you" despite your circumstances. You can be forced to fight in a war you don't want to, but you can always run away and take a chance. Living authentically doesn't mean you are not bound by laws of the universe and of soceity but rather what you do despite that. Ultimately "you" will be inspired by everyone around you or value systems you engaged with but that doesn't strip away your individuality inherently.

Kind of touches on what Camus and Sarte mean to live your life in good faith.