inner child

noun1

1. •
   The childlike aspect of a person's psyche, typically, the personality and the memories of one's childhood, especially in the context of coexisting with, and being suppressed by, an adult aspect of the person.

   • I will start by stating that most of the time — especially in our relationships — it is not our adult self, but rather our inner child, who is actually running the show. We all have an inner child. — 2010