Romans 5:12

Romans 5:12  Therefore, just as sin entered the world through one man, and death through sin, and in this way death came to all people, because all sinned—

Sin entered the world through Adam and this caused death for Adam just as God had warned him.  He ate of the forbidden fruit and it caused death to come to him and the entire human race.  This fact is referred to as original sin and is also called the “fall” of the human race.  While Adam was not created a sinner this caused all human beings from this point on to be born sinners.  It is just a matter of a short time before actual sins will come from all human children.  We are not sinners because we sin… rather we sin because we are sinners. 

We are born in Adam and in sin.