However, genetic ascension is already considered a fairly weak ascension path. Therein, the whole point is to modify your species for various tasks. That you effectively can't do it for leaders, even when the traits and lore are there, to me feels more a bug caused by oversight, than a feature.
After trying a few times to keep population of leaders as small as possible I found this way:
- Put all cool leader perks on your main species
- Start with sync evolution civic
- Forbid migration for your main species
- Set your secondary species to residence / caste (residence) (slavery would be unwise for this path, even if you choose to be xenophobic)
- Colonize only with your secondary species. They have bonus to minerals and food, and -10% energy is manageable. Science will suffer, but most people sacrifice it anyway
- Win a war or get some primitives - now you have a third race without huge -science penalty. Use them for science and maybe energy. Set them to residence / caste (residence) too
- Never research synth leaders, even if you spam synths
Because of the last one synth evolution is not good for that empire, but both bio or psi are good.