Every one of us. For we are born into sin handed down from Adam and Eve. This is called Original Sin and is inherited from the beginning of time. Catholic parents, aware of this, bring their infants to be baptized to cancel Original Sin and introduce them into the family of Christ. As babies grow to older ages however, they begin to acquire new sins.
Humanity is sinful by nature.
It is only through God's Grace that we have the means to rectify this. With the Sacrament of Confession we redeem ourselves in God's eyes. This is always made available to us. No, we do not if we use God's gift of confession. For those who truly mean it God will always forgive.