I am very easily influenced. If I go to a Shakespeare play, I end up writing in a bad imitation of Iambic pentameter.  If I talk to someone with an accent, I end up with the accent.  I think it's just part of the creative process....writers have to be able to wear different characters just as actors do and I think that ability to mimic someone else is just part of absorbing all we can into our systems so we can write from different points of view, and different emotinal states. We would be really boring if we could only write as ourselves and in one tone, don't you think?

I think you're insanely creative, but I wouldn't look for a cure.