1982's exploitation cheapie The Beast Within was remarkably terrifying for the time. The plot is a slow burner, but it's a good one. When a young couple's car breaks down in rural Mississippi, the woman is brutally raped by a mysterious assailant, who is never caught. Fast forward seventeen years into the future and the spawn of that union is entering puberty and becoming violently ill as a result of a defective pituitary gland. The family returns to the scene of the crime to track down the rapist and take him in for examination, but things quickly go very, very wrong. It's an unusual and very Lovecraftian setup that could work well with today's genetically-obsessive culture.