Inherited traits are always inherited. Humans produce humans. Adam's corrupted nature is inherited by all his descendants. It is the inability to not sin that is inherited by Adam's posterity.

Before the Fall, Adam had the ability to not sin. Following the Fall, Adam and his descendants are unable to not sin. Only the regenerate are restored to Adam's state before the Fall. The Bible calls it being "dead in trespasses and sins," not "sick." The natural man is helpless, a slave to his inherited nature - a slave to sin.

"Total depravity" does not mean that the man is immersed totally in depravity, but that the man himself - the total man - is depraved, body and soul. He is capable only of evil. His nature must be changed first (through death and rebirth - accomplished for us by the second Adam, Christ - before he is capable of anything else.

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