> But most pro-life activists use ideas like "DNA deines an organism" and "conception is the first creation of an new DNA code" to support the idea that conception is the beginning of human personhood, which is all very well and good except it doesn't jibe with intuitive definitions of what human personhood is about. . . . I personally have found that to me the definition of human personhood that makes the most sense defines a person as an individual capable of thoughts or at least brain activity.

That's an interesting definition, but like most definitions that attempt to draw a line between fetushood and babyhood, it's very vague. Exactly how could a doctor go about determining whether or not a fetus is thinking? So, I urge you to consider this: when a sperm enters an egg, something happens which I can't comprehend and the DNA from both gametes converge to become one. This creates a set of DNA which will never, ever be made again. So, right there, you have a very unique and extremely individual person.

> After all, an ovum, in its own way a potential person, dies every menstrual period; millions of spermatazoa, all potential people, die every time a man ejaculates.

Well...no. You'd need a complete set of human DNA for a "potential person".