The Automatic Hate (2016)

When Davis Green's (Joseph Cross) alluring young cousin Alexis (Adelaide Clemens) appears on his doorstep one night, he discovers that a side of his family has been kept secret from him. Against his father’s wishes, Davis travels to rural, upstate New York to meet his other cousins. While wrestling with a taboo attraction to one another, he and Alexis attempt to reunite their families, uncovering the reasons behind a long-standing rift and the shocking secret that tore their fathers apart. Together, their discoveries force them to confront the temptation to keep their familial grudge going rather than end it.

Source: TMDb