NotSoFantastic has got it exactly right.
Well, I'm not so sure. Some people might have been fixated on aeroplanes since they were in the womb, but that doesn't make them any more likely to succeed than someone who has a passing interest at 21 and decides to investigate further. A pasing interest can remain just that, or it can be the seed that grows to become a successful career in aviation and a lifelong passion. I vaguely recall that one Prooner had little interest in flying until receiving a trial flight as a gift (can't remember who it was off-hand) and the fatal attraction developed from there...
Everyone has to start somewhere.