We are all descendants of, and genetically contained in, Adam. What he did, and its results in effect on human nature, are passed to all od his decendents. Pick up a newspaper: is man's basic nature good? Hardly. Could that be a result of what happened because of the Fall, which is written allegorically?
As Jar has pointed out, Adam is an old tribal myth, as is "the fall."
Both are just as historically accurate as Romeo, i.e., not at all.
And as I pointed out many posts above, the idea of "the fall" and "original sin" and the inherently evil nature of mankind are themselves evil ideas, probably the most evil ideas ever conceived and foisted upon us by the fevered imaginations of our shaman class.
Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.