Q. Why is a Jew one who is born of a Jewish mother, rather than a Jewish father?
A verse in D’varim (Deut. 7:3-4) is quoted as the origin of matrilineality. The verse refers to “your son” as the child of an Israelite mother, implying that if the mother is not Jewish the child is not “your son” in a halachic sense.
Lord Jakobovits offers four reasons for matrilineality: “The certainty of maternity must be set against the doubt of paternity, however small this doubt may be”… “The mother’s bond with her child is firmer than the father’s”… “The mother has the superior influence on the child’s religious development”… “Jewish law, unable to recognise a mixed marriage as religiously valid, technically regards the child as legally having a mother only” (The Timely and the Timeless, 1977, pp. 198-217).