And here's the one major point of contention that I have with your statements in this post. DNA simply doesn't actually show that in a meaningful way. It does provide a point of distinction, yes, but not of the sort that properly indicates or requires separation. What it looks like to me is that you were casting about trying to find a pretext to argue against something that you felt undermined your position and latched onto DNA. Given the specific case of a zygote or embryo is fundamentally that of a potential individual in development, that looks like what you actually want to highlight more. As for DNA, as I've poked at multiple times now, biology is messy. Having different DNA does not automatically mean that something can reasonably be considered separate from an organism. Mitochondria makes for a rather common example of that, before getting to things like obligate symbiotic relationships.