Voting for your own photos?

Hi all

Forgive me if this is a redundant and/or stupid question, but I am new at the Challenge-thing. I read a little here about dates of photos and cheating, but my question is about voting.

My question is simple: Are people allowed to vote for their own photos? If so, is that fair? I mean, that sort of skews the vote results, doesn't it? Even a little? Is it ethical?

Thoughts? (or am I opening a can of worms?)

JD