Hon. Harriet Hepburn-Stuart-Forbes-Trefusis

Kolme muuta mielisairaalassa olevaa sukulaista, Idonea, Etheldreda ja Rosemary, olivat Nerissan ja Katherinen äidin siskon lapsia eivätkä siis sukua kuningattarelle ja tämän sisarelle.

Three other mentally disabled cousins also lived in Earlswood Hospital. Harriet Hepburn-Stuart-Forbes-Trefusis (1887–1958), sister of Nerissa and Katherine's mother Fenella, married Major Henry Nevile Fane, and 3 of their 7 children lived in Earlswood Hospital: Idonea Elizabeth Fane (1912–2002), Rosemary Jean Fane (1914–1972), and Ethelreda Flavia Fane (1922–1996). Prof. David Danks, then director of the Murdoch Institute, thought that a genetic disease may have killed male members of the family in early childhood and caused mental retardation in females. In 1996 the surviving cousins were moved to Ketwin House care home in Surrey; when it closed in 2001, they were moved to another