the number of biological men with absolutely no hair on their chest at all due to genetics is estimated to be around 5%, and the variation is heritable.

i cannot explain this with heredity - the men on both sides of my family are all very hairy. my dad's side is italian and jewish - very, very hairy people. 

so, again - was i switched at birth? was my mother raised by somebody who wasn't her father? these are possibilities, however obscure.

but, the fact is that the most likely cause is low testosterone - and if you want to get around it, you need to question my ancestry in some manner.