You've left out some of the important plot points dear friend. The story is about the world transitioning from non genetically modified humans to the genetically modified. Hawke was born pre modifications; his brother came after.

Of course, not everyone is modified (money makes it impossible for everyone) but it's important to the movie that the question lurks in the background--is it a bad change that society is going through in the movie's timeframe? The first question is that even with good changes Law gets depressed and almost kills himself. Hawke can't understand it. The 2nd is that Hawke wins the swimming race because "I didn't think about coming back". Can genetics create that most important human characteristic?

Does genetics change what it means to be human? And does it even succeed? It's one of the greatest science fiction movies ever made. Indeed, I'd say the greatest in my adult life.