Gattaca: Irene's Use of Jerome's Genetic Material Explained

In the movie "Gattaca," Irene uses Jerome's hair samples (along with skin cells and blood) to pass him off as valid when going to interviews for a new job she wants. Since Jerome is a "valid" (genetically superior), his genetic material allows Irene to circumvent the genetic profiling used to discriminate against "in-valids" (those with genetic imperfections).