Twelve and Holding (2005)

a.k.a. 

Disabilities:  Birthmark, Anosmia

Comments:   There are twin brothers, one is very forward, the other who has a large birthmark on his face keeps to himself. An arson attack on their tree house results in the outgoing brother dying. This brings about a transformation in the surviving brother.
A boy who fell out of the tree house during the arson attack is diagnosed with anosmia, loss of smell and ability to taste.
Definitely recommended.

http://www.imdb.com/title/tt0417385/
http://movies2.nytimes.com/2006/05/19/movies/19twel.html