[Politicalmom]

Notice they are all wearing Gryffindor colors. Some people have been questioning that, because Wormtail "went bad" and that isn't supposed to happen except to Slytherins.

[Tanniker Smith]

I think any wizard can "go bad", but it's more likely for Slytherins because they're the most ambitious. Slytherin turns out "great" wizards that do "great" things, so long as you remember the definition of "great" as something other than "really, really good".

Look at whatsisname from book 1. THere was no indication that he was a Slytherin, and I believe that he was in charge of either Ravenclaw or Hufflepuff.

TS

[andyssister]

I don't think only Slytherins can go bad. That would be too obvious. We don't know (at least I don't) what House Mundungus or Umbridge or Fudge were in as students. And Percy is a bit of a question mark!

JKR has stated many times through Dumbledore that it's all about choices. The Sorting Hat wanted to put Harry into Slytherin, but he begged for Gryffindor.He's also a Parselmouth but that doesn't make him a bad guy.