Prolifers, in what situation is it morally acceptable for a woman to abort pregnancy?

Makes a definitive statement. Says that definitive statements like that can’t be made.
Umm…yeah.

You can (and must) draw definitive legal lines regardless of the philosophical ambiguity.

Their DNA is 100% human. What does one call life comprising 100% human DNA?

Joining together is arbitrary, since the cell splits again soon after.