After what may have been months or even years, Eve listened to the lies of the serpent and finally gave in. “So when the woman saw that the tree was good for food, that it was pleasant to the eyes, and a tree desirable to make one wise, she took of its fruit and ate. She also gave to her husband with her, and he ate.” (Genesis 3:6) She was deceived and went by her senses. She saw with her eyes, and what she saw looked pleasant and desirable, so she took of the fruit and ate.
The books of 1 Timothy 2:14 and 2 Corinthians 11:3 agree that Eve was deceived. But Adam wasn't. He just flat broke the rules and sinned. The Genesis account clearly states that he was there. “She also gave to her husband with her, and he ate.” He was with her, and he was responsible for her. Romans 5:12 credits Adam for the sin, not Eve. “Therefore, just as through one man sin entered the world, and death through sin, and thus death spread to all men, because all sinned.”
The Bible says fruit, it never says there was an apple, but it really doesn't matter. The original sin was disobedience to God's command. Whatever someone wants to propose as the act that has come to be called the original sin, however logical, is still speculation. It could have been any other condition allowing Adam and Eve the option to either obey or disobey God. They both disobeyed God, and it was by their own choice. God gave mankind freedom of will, the right to choose, and, for the most part, mankind has made wrong choices. But God can't be blamed for that. There have always been plenty of warnings. “In the day that you eat of it you shall surely die.” That's a warning.
God is still warning. “Do not love the world or the things in the world. For all that is in the world -- the lust of the flesh, the lust of the eyes, and the pride of life -- is not of the Father but is of the world.” (1 John 2:15, 16) Human nature hasn't changed. People are still enticed by things they see, things that are pleasant to the eyes, and desirable. But, as Shakespeare wrote, “All that glitters is not gold.” It's always best to obey God's Word.