Gattaca (1997)

Gattaca is quietly one of the smartest films on this list. Even the title is spelled with G, A, T and C - the four letters of DNA. It imagines a world where your genes decide your future, and anyone conceived the old-fashioned way is written off from birth. The scary part? Very little of it is far-fetched now. Screening embryos for genetic conditions is already possible, and DNA testing is everywhere. Where the film is a bit generous is in how much it assumes our genes decide - in reality, most traits depend on lots of genes, our environment, and plenty of luck. But then again, that's really the point of the film. It's cool and a little cold, but it stays with you.