Throughout human history, it's been in our nature to discriminate or to label a certain group of other humans as "less than". If history was a top hat, I need only to reach in blindfolded and I could pull out an example easily. From the Crusades to World War 2 and The Holocaust, human history is rife with people telling other people I'm better than you because I hate things about your life. Or the much more dignified, "This is how one should be, and if you don't want to be taught, then you must want to die".
While watching Gattaca, one can't help but be moved at how accurate they depict the actions of a society that finds itself essentially split down the middle. Essentially, in the film, people are split into two groups: In-valids and valids; people who have genetically altered since conception to be "better" and those who are "natural births", or "god child" (the films term). In Nazi Germany it was the Aryans and the Jews; in radical islam it is Muslims and the infidels; and even right here in America it's become Red vs. Blue.
All through out known history there has been cases of society after society segregating themselves, because of percieved flaws one side has over the other. Certainly, it is no surprise the author George Annas said: "...If history is a guide, either the normal humans will view the ‘better’ humans as the other and seek to control or destroy them, or vice versa” (The Man on the Moon), when theorizing on what affect the appearance of genetically altered humans would have on society.
And this is the hidden beauty of the film Gattaca. Simply browsing human history tells us that no doubt, should a world like the one depicted in the film ever become reality, what is portrayed is what would happen; George Annas would be right. And too the film historians of the Future, Gattaca changes from a mere glimpse into what could be, to a movie ahead of it's time in prediction human events.