May a Jew by choice sit shivah and say kaddish for their non-Jewish parent?

To answer this question we must address two issues: (1) What is halakhah’s view of the parent-child relationship in these cases? The gemara states, “A person who converts is like a newborn infant,” (Yevamot 22a). In other words, a convert is unrelated halakhically to his biological father and mother. Should we read this statement in absolute terms or is halakhah cognizant of the biological and emotional bonds between parent and child regardless of legal definitions? (2) Do our halakhic and religious obligations direct us to mourn the