I’d recommend reading the ‘Red Rising’ trilogy of books. Science-Fiction of course but it gives an account of the changes to society that the human race felt necessary to conquer space. As you say, no room for passengers within a colony on another planet. Ultimately the off world colonies defeat those of earth and bring about a society where all people are born into a sect (colours) ruled by the super human ‘golds’.
Of course they are gold..... :D
Honestly, I don't think we are going to get anywhere near off-world colonies that are viable - we are too violent.