God said not to it from the tree and they did.
See Genesis 3
That is the Bible saying so. And not only that, it is your interpretation of the Bible saying so. Other Christians treat that as a morality tale. It is a pity that you are so literal. It keeps you from understanding the Bible.
Do you realize that the parables were not stories that actually happened? There are even verses about it. They were stories that were told to teach a lesson. It only shows that you do not understand:
"All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work."
That does not say or imply that the Bible is literally true. It only says that it is "profitable for teaching, for reproof, for correction, for training." Genesis and Exodus still work if one treats them as morality tales. They do not work if one treats them as being literal. Then you are once again calling God a liar.