Is "personhood" a cultural or a scientific category?

The argument that a potential human adult should be given the status of "person" from the moment of conception is being frequently made by people who wish to make abortion and human stem cell research illegal. While "personhood" is a cultural and not a scientific category, biology is often being used to justify such claims. Biologists, however, have not reached consensus on this issue, and this talk will discuss some of the places where different groups of biologists have claimed "personhood" begins. These include fertilization, individuation/gastrulation (when the embryo can no longer form twins), the acquisition of the human-specific EEG pattern, and birth. The rhetoric surrounding the fertilization issue concerns the photographs of prenatal life and the cultural representation of DNA as our soul or essence.