You can call original sin knowledge if you want to but this is not exactly true. According to the fable in Genesis, Eve was talked into eating a fruit that gave her knowledge and she also made Adam eat. God was not pleased and had told them not to eat of that tree. It makes you wonder why the tree was in the garden to begin with.

Evangelicals claim we all have "original sin" and it breaks down like this. Adam and Eve had to live a very long time for us have enough people on earth to populate the planet. Genesis claims they had advanced age in those days and the conclusion of population is incest. That's right. The all knowing perfect god had his earth populated through INCEST. All the serpent did was help impart knowledge to god's creation. Baptism is the symbolic washing away of all of this, but that came much later.