"Names are overrated. I'm me!" - Cat from Coraline (approximate quotation)
From the tree, that is. I don't believe the leaf often falls; it either is thrown by said tree, or it jumps. Let us examine both:
THROWN. Say one's parents want one to become a doctor. Horribly cliche, I know, but for the sake of argument I'll use it. One really wants to become an accountant, but is eventually coaxed into attending medical school. The parents have thrown one in that direction.
JUMP. Now let's create an alternate reality in which one breaks the chains of influence and becomes an accountant. The parents might be dismayed, but screw them! An unchanging line is boring, yes? Now if one was willing to become a doctor, that would be different.
Unfortunately many seem to be thrown, whether it is consciously or not. Not necessarily in terms of career, but also in disposition. Oftentimes a jerk will be the child of a jerk or two. It's sad but true! Not always, but too close to it. I've already broken some of my family's influences, such as being presumptuous (I'm working on the communicating-with-others bit). Not to say I don't love my kin, but I don't intend to become their carbon copy. My mother suggested I become a lawyer someday. While it may be a fascinating career, it's not my aim.
In other words, my personal belief is to do what one wants, not what one's parents want. Unless circumstances say otherwise, like in poorly-run countries where one is stuck in a cycle.