It’s mainly there for story and worldbuilding , not shock value alone. In Game of Thrones , incest helps show how the Targaryens try to keep power and dragon-riding bloodlines “pure,” while the Lannisters’ secret relationship drives major plot twists and moral conflict.

Why it shows up so often

  • It reinforces the idea that Westeros is a rotten, power-obsessed world where noble families break social rules to preserve control.
  • It gives the Targaryens a defining trait: family marriage as tradition, tied to their claim of exceptional blood and dragon heritage.
  • It creates dramatic consequences, especially for the Lannisters, because the secret relationship shapes the opening conflict and much of the early political chaos.

What it does in the story

  • It makes the audience uncomfortable on purpose, so the show can underline how twisted elite power can become.
  • It adds tragedy: characters often see their relationships as normal, sacred, or politically useful, even when the audience knows they’re crossing a taboo.
  • It supports the larger theme that inherited power often comes with corruption, instability, and painful consequences.

The bigger reason

The series uses incest as a symbol of dynastic decay. It’s not just about sex; it’s about families treating people like bloodline tools, and that fits the show’s obsession with power, inheritance, and collapse.

In plain English

The show uses incest because it’s one of the fastest ways to show that this world is politically brutal, morally warped, and built on families sacrificing everything for control.

If you want, I can also break down the Targaryen side vs. the Lannister side in a quick table.