When one considers the ethics of manipulation, the question of whether we ought to, or whether we may manipulate an organism or entity depends on the answer to the first and most fundamental question:
What is it?
Ascertaining the identity and status of the object of our intended manipulation is essential.
In the fields of obstetrical medicine and reproductive medicine the ethical debates have raged for four decades. Enlightened discourse between opposing parties must assume good motives by all involved, and then go about asking the essential questions, following where the truth of science and reason lead.
Many claim that life begins at some point distant from fertilization, always beyond the point at which they propose some manipulation (abortion, embryonic stem cell culturing, etc…). There are always a list of biological functions that are given to define when human life begins: Cognitive capacity, etc.
The simple biological truth of the matter is that the Cell Theory states that all cells arise from pre-existing cells. There is no blackout period between sperm and egg uniting, and then the emergence of ‘life’ at some point distant.