Orthodox Judaism and Conservative Judaism follow the Halakha, deeming a person to be Jewish if their mother is Jewish, or they underwent a proper conversion.Reform Judaism and Reconstructionist Judaism accept both matrilineal and patrilineal descent.However, there are differences in interpretations when it comes to non-Orthodox Jewish denominations in the application of this definition, including According to the Mishnah, the first written source for halakha, the status of the offspring of mixed marriages was determined matrilineally. He brings two likely explanations for the change in Mishnaic times: first, the Mishnah may have been applying the same logic to mixed marriages as it had applied to other mixtures (kilayim).
Because rabbis in the other movements do not require that converts make this commitment, Orthodox authorities do not generally accept as valid conversions performed outside the Orthodox community.Conservative authorities likewise require that conversions be conducted according to traditional Jewish law.This policy is commonly known as patrilineal descent, though "bilineal" would be more accurate.In 1983, the Reform Central Conference of American Rabbis passed the Resolution on Patrilineal Descent, declaring that "the child of one Jewish parent is under the presumption of Jewish descent.According to halakha, a Jew by birth must be born to a Jewish mother.
Halakha states that the acceptance of the principles and practices of Judaism does not make a person a Jew.
If both parents are Jewish, their child will also be considered Jewish, and the child takes the status of the father (e.g., as a kohen).
If either parent is subject to a genealogical disability (e.g., is a mamzer) then the child is also subject to that disability.
Most notably, the Israel Movement for Progressive Judaism has rejected patrilineal descent and requires formal conversion for anyone not born of a Jewish mother.
Karaite Judaism believes that Jewish identity can only be transmitted by patrilineal descent.
If a male is already circumcised, a drop of blood is drawn from the penis.