{OotP} SPOILER: Is Sirius a Slytherin?

[ratalman]

No: HPFGUIDX 63073

SPOILER:
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Pardon me if this is already common knowledge, but does 
canon state that Sirius was a Gryffindor?  From all indications of 
the decorations and art works, such as the serpent motifs, etc in 
the Black ancestral home, as well as Sirius' entire family tree, 
wouldn't Sirius have been sorted into Slytherin?  I guess I am 
assuming that everyone else in his family had been in Slytherin.  
This has been worrying me!  Obviously Harry was able to choose 
Gryffindor over Slytherin, so it is possible that Sirius broke with 
his family's tradition, and chose Gryffindor too. 

-Robyn