Adam fell because he no longer wished to have communion with God or trust Him.
He believed that the knowledge of good and evil would make him independent of the Lord,
like God himself. Gods warning was doing this would lead to death, and Adam chose to
die.
The truth was it was true he would die, and also he knew what was good and evil.
Knowledge without love and communion with God corrupts the soul and leads to death.
It is this we inherit from our parents, and into which we are born.
Now the delusion is we love and care, we believe we can be righteous, do the right thing
and not get corrupted. But as we grow, we shut off our love, become hardened and bitter,
and slowly decay into a sinful state.
It is this inevitability that Jesus on the cross came to resolve.
There are exceptions to this reality. John the Baptist was born in communion with God.
So he did not suffer from this break.
People born into christian families have some kind of covering because of their believing
parent. Paul talks about the children being regarded as Holy.
Some have called sex original sin, and the thing that we can never resolve.
There is some reality to this, as sexual identity and attraction between people is innate
in our existance. But marriage is a holy estate, blessed by God, and we all come out of
the union between a man and a woman.
So I see why the term original sin came into being, as if it is immovable, something
innate within man himself. But it fits that this is just the reflection of man living
alone, loosing focus because the Lord is not their to bring proper reference.
Jesus bring this to reality in the parable of the vine. We are the branches and if
we abide in Him we stay focused and alive. When we depart we shrivel and die.
Being in communion is life.
I also understand there are some who find they never attain this and their hearts
appear like a warring island, though they have faith, it does not seem to bring this
unity or communion.
For them the description of original sin, being a reality which stops them coming to
God a reality.
Our theology will in the end reflect out experience.