That is your opinion. You have nothing more to go on to support your opinion than you want it to be valid.
No, it's not an opinion, it's a values judgment. In fact, that goes to the heart of what I've been saying here: that everything hinges on what we call a "person," and that there is no objective way of determining which concept of personhood is correct. When we are dealing with values judgments, which we are here, there is no such thing as "true" or "false." A values judgment is either accepted or rejected, either agreed with or disagreed with, but it can never be proven one way or another.
When I say that personhood depends on thoughts and feelings, that isn't saying anything you can ever go out and measure and confirm one way or another. When someone says that personhood depends on DNA, that also isn't saying anything that can ever be proven, one way or another.
I can prove easily enough that an embryo at conception has no brain, and thus has no feelings, thoughts, or personality. That is a fact.
You can prove easily enough that an embryo at conception has somewhat different (although related) DNA from its mother's. That's also a fact.
Which of these facts determines personhood? That is NOT a question of fact, but a call for a values judgment.
I say that personhood depends on thoughts and feelings because I see that as being what MATTERS. When someone has thoughts, feelings, memory, personality, then that is someone who can feel pain, suffer disappointment, be afraid. It is someone who can love and be loved, whose death is a loss for someone else.
By comparison, the mere possession of individual human DNA strikes me as not very important. And that is my judgment, which as a human being I am entitled to make. If you want to persuade me that my judgment is wrong and yours is right, what you need to do is to show me why having independent DNA is so important. Because that is by no means self-evident.