where does the term grandfathered in come from
Grandfather clause The term originated in late nineteenth-century legislation and constitutional amendments passed by a number of U.S. Southern states, which created new requirements for literacy tests, payment of poll taxes, and/or residency and property restrictions to register to vote. States in some cases exempted those whose ancestors (grandfathers) had the right to vote before the Civil War, or as of a particular date, from such requirements. The intent and effect of such rules was to prevent poor and illiterate African-American former slaves and their descendants from voting, but without denying poor and illiterate whites the right to vote. Although these original grandfather clauses were eventually ruled unconstitutional, the terms grandfather clause and grandfather have been adapted to other uses.
Zhou dynasty K.E. Brashier writes in his book "Ancestral Memory in Early China" about the tsung-fa system of patrilineal primogeniture: "The greater lineage, if it has survived, is the direct succession from father to eldest son and is not defined via the collateral shifts of the lesser lineages. In discussions that demarcate between trunk and collateral lines, the former is called a zong and the latter a zu, whereas the whole lineage is dubbed the shi. [...] On one hand every son who is not the eldest and hence not heir to the lineage territory has the potential of becoming a progenitor and fostering a new trunk lineage (Ideally he would strike out to cultivate new lineage territory). [...] According to the Zou commentary, the son of heaven divided land among his feudal lords, his feudal lords divided land among their dependent families and so forth down the pecking order to the officers who had their dependent kin and the commoners who "each had his apportioned relations and all had their graded precedence""[31]