I'm glad you've enjoyed the series, but sorry you didn't appreciate the cursing. There are a variety of reasons my characters curse. I'll warn you, this is going to be long, but you asked for it :)
-As an author I think its my responsibility to add realism to books; readers have to relate in some way. Your niece and her friends might not, but most teens curse. Keep in mind my characters are 17-21 in age. My characters are, at times, running for their lives and as a reader I'd find it ridiculous and unrealistic if they said something like "darn" while in a life or death situation.
P.S. The woman I actually wrote this email for never got it because her email bounced, which reminds me to remind you guys to make sure you type in your email correctly if you want a response! I get quite a few emails that bounce back. If you don't hear back from me, please feel free to email me again. If you don't hear from me again, then that means I'm probably ignoring you :)