User blog comment:Fandom Freak002/My Thoughts/Opinions on Dragon Slayers/@comment-25693405-20141231001020

It's probably a story glitch/oversight.

I think the permanent Troia is most likely if it had to be explained, but Mashima stated that the dragon slayers all have varying degrees of motion sickness. It could only affect male dragon slayers that were actually raised by dragons, but I think making a weakness like this would be stupid.

Ultimately though, biology is complicated. Something about Wendy's biology may be suppressing it, or she might be really good at hiding it? I hope they don't have her develop it later, a story is no fun if everyone is the same. Ultimately, I don't think Gajeel should have gotten sick during the grand magic games, since he rode in the Phantom Lord fortress and on the ship to Tenrou without trouble. If too many characters get motion sickness, then it becomes, well, you know...