Gattaca shows that catergorising people into a hierarchy of castes ("superior" and "inferior") is both false and dangerous. How does this relate to...

Don't forget feminism in thinking about a superior/inferior caste system.  In the movie Gattaca, people were treated differently  based on things they couldn't control-- whether they had natural genetics, or superior, altered genetics.  Similarly, we cannot control our race or our gender, but our society CAN control how we treat people with such differences equally.

If you have ever read The Giver by Lois Lowry, you can apply the lessons in Gattaca to that book as well.  In The Giver people are given jobs based on their ability and there is a very rigid, and widely accepted, caste system.

What is more ethical about their caste system than ours, or the fictional one in Gattaca, is that their rankings are based on ability, and not on things that are out of a person's control.  They are ranked in society by the skills they could perform-- if we are going to rank people, the lesson we could learn is that we should base our rankings on ability and not race, gender, etc.