.
Jews believe that the soul is in existence before birth and that it enters the newborn as it emerges from the womb. The mother must abstain from sexual relations with her husband for a week after having a boy and two after having a girl. This has changed since it use to be a month for a boy and two months for a girl. This is a ritual of purity. The father also blesses the reading of the Torah and prays for the health of his wife and new child. If a girl is born, the father names her at this time. Boys are not named until their circumcision. Their name will often be a combination of the child's name and the father's name. The circumcision is a ritual called Brit Milah and is performed on the eighth day of life by a Mohel. A doctor would not fulfil the spiritual requirement therefore the Mohel, a trained Jew, performs the surgery. Circumcision was a commandment given to Jews specifically as physical sign of the covenant between them and G-d. Although the Torah is not clear why the eighth day is important, science has confirmed, "that an infant's blood clotting mechanism stabilizes on the eighth day after birth."(Rich, Birth) Another ritual that must be performed is the Pidyon ha-Ben. This is the redemption of the first born son on his 31st day of life by paying five silver dollars to a Kohein, a priest that is a direct descendant of Aaron.
Children undergo a rite of passage at the age of thirteen for boys and twelve for girls. This is the time when the child becomes required to observe the Commandments. This does not have to be accompanied by a ritual ceremony but commonly is now. The Reform movement decided to not have the confirmation but instead change the age of the Bar Mitzvah to sixteen or eighteen. This rite of passage can take place at anytime that the child is mature enough to be acting as an adult in any capacity.
Sin is not something that Jews believe is ingrained in a child at birth.