There are 3 directions in this game; Good Wife, Filthy and Lesbian.
- The Good Wife and Lesbian paths are compatible with each other, as are the Filthy and Lesbian paths
- Dylan, Ellie, and Patricia, the incest characters, are only on the Filthy path
- The Filthy path also include others like Sam, Zac, the college guys, etc, so it's not exclusively incest
- Therefore, if incest is not your thing, you go for either the GW path with or without Lesbian, or pure Lesbian, or Filthy without incest.
Put quite simply, there are lots of options for you and incest isn't necessarily the only direction of this game, it's just the more popular.