According to Genesis 1:26-27 Adam and Eve were created before the instructions of the tree of good and evil.
26.
And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.
27. So God created man in his own image, in the image of God created he him; male and female created he them.
Then in Genesis 3:1 it brings up Eve telling the serpent about the tree that God told them not to eat.
Genesis 3:1
1Now the serpent was more subtil than any beast of the field which the LORD God had made. And he said unto the woman, Yea, hath God said, Ye shall not eat of every tree of the garden?
2And the woman said unto the serpent, We may eat of the fruit of the trees of the garden:
3But of the fruit of the tree which
is in the midst of the garden, God hath said, Ye shall not eat of it, neither shall ye touch it, lest ye die.
4And the serpent said unto the woman, Ye shall not surely die:
So from what I am getting from the Bible they both knew equally and both choosed to disobey whether they were tricked by the serpent themselves or by the serpents influence that was allowed to be in Eve after she disobeyed. Adam could have said no, but he didn't. Adam could have been looking out for Eve, but was elsewhere. Eve could have said no, but didn't. They both had their own will to freely choose and they both freely choose to directly disobey the words from God.
That's why I said they decided to change because they had a life that was full of everything they needed, but after disobeying they received a life that meant all would have to die. Sometimes people are tempted when they don't know what something means and or don't trust/believe what is given to them and end up suffering the consequences of their actions. Adam and Eve were told that they would die. My guess this that they didn't know what dying meant until they were confronted with God and knew there was a big difference in the life they had to the life they were going to live.