Error log excerpt:

[Gene Tools - Forked] Transpile failed! Not able to find branch sequence!
GeneTools.GtPatches+GtDisableLoadChildBodyFailsafe.Transpiler(...)
...
HarmonyLib.CodeTranspiler.GetResult(...)

Details:
The transpiler in GtDisableLoadChildBodyFailsafe fails because it cannot locate the expected branch sequence in the target method's IL.
This likely happens because RimWorld 1.6 changed the IL layout, or another mod has already patched the same method.

Environment:

RimWorld 1.6.x

Gene Tools - Forked (latest workshop version)

Harmony 2.3.6

Mods affecting xenotypes/genes also active

Suggested fix:
Update the transpiler to be more flexible in matching IL (or add a null-check/fail-safe so the mod can still load without breaking).

Thanks for the fork.