Totally Fabulous by Michelle Radford

If you had the power of mind control, could you resist using it? (Didn't think so. Fiona Blount feels your pain.)

Fiona is coming to America! Her long-lost-now-found father is bringing her from London to meet his family. Of course, there's a secret agenda for her trip: Fiona has inherited her dad's psychic abilities and is off to ESP boot camp. Good thing she doesn't take after the rest of his family—a pretty moody bunch. Fiona knows she shouldn't be using her power of compulsion until she has more training, but if she can make people happier, isn't it almost her duty to do so? She's sure that with just a little bit of nudging, they'll all be on their way to being totally fabulous—but is she totally deluded?