What is Isadora's given name in the novel, Fear of Flying?

Isadora White Wing was born "Weiss;" her parents were Jewish artists, entertainers and leftists of the 1930s who had, in the 1940s, Anglicized the name, gone into business, and started celebrating the winter solstice (with a tree in the house on December 25) and the vernal equinox (with decorated eggs and baskets).