User blog comment:IamJakuhoRaikoben/Chapter 276: Chariot, Review./@comment-2106167-20120323225635/@comment-288216-20120326033723

That's because maybe the Dragon Slayer develops it during a moment in the life. They are not born with this weakness, as well as they are not born Dragon Slayers. Strange thing is that all styles are affected by it. There will be probably an explanation, since Gajeel stated he never had this problem before.