There are different versions of that story. My favorite goes along these lines:
God created the Garden and in the middle put the Tree of Knowledge then he created all the animals to live in the Garden along with humans. God let the humans have dominion over the Garden but warned that the Tree of Knowledge would make them forever unhappy if they ate from it since it would make them self-aware and overly curious. Adam was bit of a dumbass and meekly complied, but Eve was a take charge kinda gal and was already curious. Eventually she was curious enough to taste from the Tree of Knowledge. Awareness flooded through her like a wave. It both saddened her and gladenned her. Wanting to share this with Adam, she offered him a taste too. Adam, being a bit of a dumbass, would eat anything Eve gave. He, too, became self-aware. God didn't throw them out, they left like birds leaving a nest.