Rawblood

In 1910, eleven-year-old Iris Villarca lives with her father at Rawblood, a lonely house on Dartmoor.
Iris and her father are the last of their name. The Villarcas always die young, bloodily. Iris believes it's because of a congenital disease which means she must isolate herself from the world.
But one sunlit autumn day, beside her mother's grave, she forces the truth from her father: the disease is biologically impossible. A lie to cover a darker secret.
The Villarcas are haunted, through the generations, by her. She is white, skeletal, covered with scars. When a Villarca marries, when they love, when they have a child - she comes, and death follows.
When Iris is fifteen, she breaks her promise to remain alone all her life, and the consequences are immediate and horrific.