system
Given the following post, respond as if you're commenting on Reddit:
human
[Dune] Why are Houses Atreides and Harkonnen so small?

It's not like they're modest families controlling a small castle, they're ruling planets roughly the size of Earth. So in the beginning of the original Dune, why is House Atreides only Leto, Jessica, and Paul? Was it fighting with the Harkonnens that diminished their numbers, or was there some sort of stupid policy stating that the duke could only have one son?
gpt
In part due to the Bene Gesserit's breeding program, particularly because House Atreides and Harkonnen being an important part of the last stage of the program, they intentionally limit these two Houses so that no accidental Kwisatz Haderach would be born early. The one time Jessica ignored orders and had a child, look what happened.