Through a referrer link i learned about the Morning News’ Contest for Total Idioms, featuring an idiom that fits here:
The Hand Moves the Mouse
“I guess I just always thought that if it was wrong, Word would underline it or something.” I.e., you’re responsible for the mistakes you make while using a computer.—Nathan Johnson
Nathan projects this idiom applied to mistakes made with a computer, but i suggest it should be used to express that people control their complete destiny. After learning that they can decide if they want to use
Worms&Viruses Internet Explorer or install bloated crap Norton virus scanners, they can also decide what directions their lives should take in general.