Starcrossed, by Josephine Angelini.
Helen ran the charm of her necklace along its chain, and held it out for Castor and Cassandra to look at. "This is all I got from her. A piece of jewelry. Does it mean anything to you?" she asked intensely.
A part of her had always hoped that her necklace was important - that maybe someday it would answer all her questions. In her wildest daydreams she imagined it being the talisman that would someday guide her to her mother. Cassandra and Castor studied the heart charm carefully, but there was nothing special about it.
"It's very pretty," Cassandra said kindly.
This book seemed a lot like Twilight to me, but with Greek demigods instead of vampires and werewolves. Helen's mother left her and her dad, Jerry, when she was very little, and she has always known she's been a bit strange - she is almost 6 feet tall, and she can run super fast; in fact, she's going to try to get a track scholarship for college. When the Delos family moves to the island, however, Helen feels a weird connection to them, until Lucas Delos explains to her: they are demigods, as in from Greek mythology - and so is she.
In Twilight, Bella lives with her single father and interacts with the large Cullen family; in Starcrossed, Helen lives with her single father and is drawn to the large Delos family, comprised of a family and their cousins. She falls for Lucas (like Bella did for Edward) but they can't be together because it's frowned upon in Greek mythology, and has been for many, many years; originally, Edward's family was opposed to Bella and Edward being in a relationship too.
Starcrossed is part of a trilogy and the second book in the series, Dreamless will be out in May 2012; I can't wait to read it, because Starcrossed was definitely a treat.
4.5 stars out of 5.