This is just a guess at a possibility.  There is a world we don’t know and could not possibly understand.  In it are ”souls” and it is meaningless to say what they look like.  But these souls are assigned a baby human to “drive” or “operate” just like we, on a much simpler level, can operate a remote controlled toy car.  For sake of imagining, the soul is (to our 5 senses) an invisible point and may be inside our body, or just directing it from nearby like we follow a toy car we are steering by invisible waves.  The soul patiently sees the human body materialize from a few cells though absorbing and processing (metabolism) develop and grow through childhood to an adult.

The soul DECIDES what the human can do.  The “volition” aspects of what to put in the mouth, where to go, and what to say. How to behave and act.  Beyond the control of an individual soul is a surroundings, both inanimate and living, and other souls controlling other humans.

The souls are doing a test.

Typically that lasts 70 years, and maybe more.  Sometimes the soul gets an early mark.  Or hardly needs a test at all.

Added 2 weeks later (6 days before Christmas 2015). The testing area (planet Earth) was so chaotic that about 2000 years ago the Creator sent his own sentiment down as a dot to be one of these humans and show them how they should act.  We call him Jesus.  And he took the blame for how we stuff up and if we accept Him as a role model, we will pass the test.