In the 17th century (or 18th, I forget), Scientists picking
   apart the physical brain saw physical analogies between the
   brain and the human reproductive system.

   That's where our "concept" that ideas are babies started.

   [actually, it started in King David's time at least: One of the
   Psalms has the line, "Dash the little children against the
   rocks" - and he was speaking symbolically about smashing bad
   ideas within your mind before they get too far.

   Brain makes babies called ideas through conceiving. So, I guess
   it's just a basic part of how we think in Western Civilization,
   culturally imbued, but what can we dood?