http://terraria.gamepedia.com/Guide:Containing_the_Hallow/Corruption
http://terraria.gamepedia.com/Hardmode
http://terraria.gamepedia.com/Clentaminator
Firstly: The initial "V" of Hallow/Corruption/Crimson.
Most notably, notice the picture: picture http://hydra-media.cursecdn.com/terraria.gamepedia.com/8/8c/Contained_Corruption_and_Hallow_World.png
IIRC, the V is "centered" on where you killed the Wall. So move the wall left, or right and follow it at an angle to your house. I may be wrong on that part. this states that Immediately, two diagonal stripes of the new biomes generate, replacing large sections of the World in a "V" pattern that extends from the center of The Underworld all the way to the surface.
Things might have changed with 1.3, but most likely your house is near one of the "Sides" of the V.
Secondly: When you "smash" an alter you create small pockets of one or the other:
Upon smashing a Demon/Crimson altar with the Pwnhammer (Or more powerful tools later on in the game), there is a chance of a single block of your world turning Hallowed or Corrupt/Crimson in a random place, which given enough time, will spread to form new, large areas to deal with.
So the basic gist is that your house is in a "bad"/"unlucky" place. The biomes can spread - either with time or smashed altars+time - but if your house was "immediately" in a spot, it's all location.
You can remove the corruption, the easiest method is a clementator - which spray changes an area into a biome of choice.
http://terraria.gamepedia.com/Clentaminator
The Clentaminator is the fastest means of spreading Hallow, Corruption, Crimson, and Mushroom Biome, or purifying biomes of Hallow, Corruption, or Crimson.
You can also clear a surrounding area - 3 blocks to stop the spread - and turn your home area into something like Jungle or Mushroom Biomes.