Like you can't just unlock all the entire psycast path without cause, it's illogical (yea ik this is rimworld lol but...).

With this patch/mod, your psycaster will be limited based on their genes.

For example your pawn has a special gene called "Staticlord" and it will unlock "Staticlord" path without unlocking other psycast paths.
but there possibly can be multiple psycast genes in one pawn.

Factor:
• Parent's Genes (If you watch Avatar:The Last Airbender or Naruto, they're all based on parent's genes concept)
  
• Biomes (example if you born in tundra or ice sheet, chance for getting "Frostshaper" gene is increased)
  - this will effect on NPC Factions location as well
  
• Xenotype (If you born as an impid, chance for getting "Conflagrator" gene is increased)
  Example
  Baseliner: Random
  Pigskin: Random
  Impid: Conflagrator++, Random
  Neanderthal: Protector+, Random
  Dirtmole: Nightstalker, Random
  Genie: Technomancer++, Chronopath+, Random
  Yttakin: Frostshaper+, Wildspeaker+, Random
  Hussar: Warlord++, Random
  Highmate: Empath, Archon, Random
  Waster: Necropath+, Random,
  Sanguophage: Necropath++, Nightstalker+, Harmonist+
  
  ++ = Major Chance Increased of getting respective psycast gene
  + = Minor Chance Increased of getting respective psycast gene
  
  Random/Unknown: Archotechist, Skipmaster, Staticlord, Animat, Insectorator, Puppeteer, Gauwalker

*note: Sorry i'm not detailed at this but at least i give you a view about this concept.