Forbidden by Tabitha Suzuma.
Here's the synopsis: "She is pretty and talented - sweet sixteen and never been kissed. He is seventeen; gorgeous and on the brink of a bright future. And now they have fallen in love. But... they are brother and sister.
Seventeen-year-old Lochan and sixteen-year-old Maya have always felt more like friends than siblings. Together they have stepped in for their alcoholic, wayward mother to take care of their three younger siblings. As defacto parents to the little ones, Lochan and Maya have had to grow up fast. And the stress of their lives—and the way they understand each other so completely—has also also brought them closer than two siblings would ordinarily be. So close, in fact, that they have fallen in love. Their clandestine romance quickly blooms into deep, desperate love. They know their relationship is wrong and cannot possibly continue. And yet, they cannot stop what feels so incredibly right. As the novel careens toward an explosive and shocking finale, only one thing is certain: a love this devastating has no happy ending".
Um...can you see why it's HIGHLY controversial? A lot of people simply can't stand to read it, and I'll admit: I fel VERY nauseous at points. But the writing was brilliant and I was dying for a way for them to be together, wishing DESPERATELY that they weren't related.
And don't get me wrong! This is NO cheesy YA romance book! This is beautifully written and horrendous and deep and emotional...it's just something else.