Since that time every human being has been born separated from God.  The Bible teaches:

"Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned" (Romans 5:12).
"And you hath he quickened, who were dead in trespasses and sins" (Ephesians 2:1).

Every person receives a sinful human nature from his parents as well as a body.  This is why people don't have to be taught to sin and break God's law; it comes naturally because of our sinful nature.

THERE ARE THREE REASONS WHY WE ARE SEPARATED FROM GOD

1.  Our sinful human nature separates us from God.
A human nature equips us to understand man, but not God.

"But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned" (I Corinthians 2:14).

We must have a divine nature in order to fellowship with God.  This is why we must be born again:

"Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God" (John 3:3).

When you are born again, you are born into God's family and you receive God's nature.  Until then, you are separated from God.