Ego’s “Neural Pathway”

Peter was actually very curious. As fellow captives, Gamora, Rocket Raccoon, and the others had clearly been controlled by Ego through some method. As for that method, the first thing Peter thought of was the Soul Stone. The Soul Stone could alter Ebony Maw and Thor's memories at the soul level. Completely rewriting Gamora and the others, making them serve Ego from then on, did not seem difficult either. But why had Baby Groot remained unaffected?