Q. Everyone knows that the child of a Jewish mother is regarded as Jewish regardless of who the father is. If both parents are Jewish, does the father determine any aspect of the child’s Jewish identity?
If the father is a non-Jew, the child is an Israelite even if the mother is from the family of a Kohen or Levi. If the father was born a Kohen but has compromised his status by entering into a union with, for example, a divorced person, he becomes a Halal and his son is not a Kohen.
The child of (a) parents who are within the forbidden degrees of incest, or (b) a Jewish woman who, though still married to a Jew, had relations with a Jewish man other than her husband, is a mamzer. The mamzer is Jewish but has certain disqualifications when it comes to marriage.
A child born out of wedlock – i.e. where the parents were not, but were eligible to be, married according to Jewish law – is not a mamzer.
Since in Jewish law a person cannot indict him- or herself, a woman’s confession of adultery is not evidence unless supported by legally acceptable indications. The Shulchan Aruch (Even HaEzer 2:2) says, “Those who are constantly disqualifying others as mamzerim are themselves under suspicion of being mamzerim, because people who are in the habit of disqualifying are only projecting their own defects onto others.”
It adds, “People who are arrogant, cruel and misanthropic and do not treat their fellows with loving kindness are of questionable lineage, for Jews are supposed to be characterised by modesty, compassion and loving kindness.”