An arabesque on the usual formula

A curious detail at the end of the NYT obituary for Eva Ibbotson, whose father was a physiologist who did pioneering work on artificial insemination:

Survivors include three sons, Piers, Toby and Justin; a daughter, Lalage; two half-siblings, Jonathan and Ruth, from her father’s second marriage; and seven grandchildren.

Because of her father’s dedication to his work — “Thanks to DNA profiling,” Piers Ibbotson said on Tuesday, “it’s been established that he did indeed ‘draw on his own resources’ ” when outside sperm donors could not be procured — Ms. Ibbotson is also survived by an additional raft of half-siblings whose precise number is unknown.