I am a Doctor. I do not kill individuals. I am a Pediatrician.
Unlike most of my colleagues I have had the opportunity of deepening my knowledge on what is known as Developmental Biology: I have two Doctorates on that subject (one from Europe and one from the USA). This is the scientific field which studies the start of Life and the complex process that follows: the process of development.
Personhood is a Philosophical/Theological and Legal term. As a scientist I can’t demonstrate Personhood in a laboratory.
All I can do is to prove that this ‘organism’ is an Individual of the Human Species (or whatever species you choose)...