Children of Tomorrow

Children of Tomorrow is a 1970 science fiction novel by Canadian-American author A. E. van Vogt.

Plot summary
Commander John Lane returns from a ten-year mission in space to find that the teenagers of Spaceport City have organized themselves into "outfits", well disciplined, non-violent little gangs with their own customs and argot, and that the parent's role in teen upbringing has become minimal. His 16-year-old daughter Susan belongs to the Red Cat Outfit, whose newest member Bud is actually a spy for the alien fleet that has secretly followed John Lane as he returned to Earth.