You argue that there's no evidence to prove it's not a human life, I argue that there's no evidence to prove it IS a human life. It's an extremely debatable subject.
What is NOT debatable is that the pregnant woman IS a person with rights, therefore, the law must err on the side of the woman until such a time in the pregnancy as most people can agree that the fetus deserves rights.
Yes, an individual and unique DNA pattern is there, however, there's no guarantee that that will result in a birth. There are many genetic disorders that will cause an automatic miscarriage. For instance, if a 3rd copy of any chromosome except 21 and two others is present, a miscarriage is guaranteed to occur, and a 3rd copy of those other two will result in a baby that will live no more than a year. Only a 3rd 21st chromosome will result in a person that will live, albeit with Downs.
So just because a unique DNA pattern is present does not mean a viable birth is present, and I would hardly say that a 3rd month miscarriage equals a human life having been in existence. If that was the case, women would have miscarriage funerals.