As I said American Slaves were affected by this wretched opinion that others get to define personhood.   Abortion is just a trendier manifestation of a bad idea.

The question boils down to "unique and complete identity".

A fertilized ovum has a totally unique, and totally complete identity.   The unique and complete set of genes DRIVE all further development from the moment of conception.

No further "identity" needs to be added at any point.  Development doesn't drive identity...Identiy drives development.  It's full and it's complete and it's unique.  Even so called "identical" twins have slight differences from the outset.

No need to resort to ensoulment.