Full Idea
How could a person originating from different parents, from a totally different sperm and egg, be this very woman (Elizabeth II)? ..It seems to me that anything coming from a different origin would not be this very object.
Gist of Idea
It is a necessary truth that Elizabeth II was the child of two particular parents
Source
Saul A. Kripke (Naming and Necessity lectures [1970], Lecture 3)
Book Reference
Kripke,Saul: 'Naming and Necessity' [Blackwell 1980], p.113
A Reaction
Since baby Elizabeth could have been smuggled into the palace in a bedpan, it seems to me that her properties now are rather more obvious than her origin. I fear the only necessity here is that you can't change the past. An intriguing puzzle.