Matrilineal Descent in Judaism and its Biological Basis
Historically, various societies had either matrilineal or patrilineal descent. Judaism recognizes both patrilineal and matrilineal descents but in different contexts. Jewishness is not determined by faith or by observance; it is inheritance as a matter of birthright. God chose a Jewish family, rather than an ideology, as the basis for the nation. Outside of conversion, ge’ur k’halachah, Jewishness is passed down strictly according to maternal line. In the spheres of family inheritance and tribal belonging, the lineage is determined patrilineally. Jewishness, however, is not connected to land ownership or any other material inheritance. From a spiritual point of view, a Jew is the one who possesses a Jewish soul. How this spiritual distinction is reflected in the biological relationship between parents and children is the subject of this paper. We analyze here sources from classical Jewish texts, Kabbala and Chasidic philosophy of Chabad, which describe the predominant physical influence of a mother on a child. We discuss this asymmetry and its mechanisms in the biological systems using recent discoveries in the areas of maternal genetic effects, mitochondrial inheritance, and epigenetic influence. The immense influence of a mother during embryonic development, as well as during early childhood, on the physical and psychological development of the offspring clearly illustrates the maternal mark on the spiritual development of a child. The examples from Jewish sages are exceptionally predictive of the modern scientific discoveries.