The primary ethical dilemma that is brought up in stem cell research is concerning the source of embryonic stem cells (hESCs). As the name states, hESCs come from embryos. To be more specific, they come from the inner cell mass of a blastophere, which is the beginning stage of an embryo. However, that mass of cells could have the potential to give rise to human life, and there in lies the problem. Often, this argument leads back to a similar moral debate held around abortion. The question is: when does a mass of cells gain personhood and autonomy? Some individuals believe that an embryo is in fact a person at the moment of conception and that using an embryo for anything other than creating a baby would essentially be killing a baby. On the other end of the spectrum, people argue that the small ball of cells at that point only has the potential to become a fetus, and that potentiality, even in natural conception, is far from guaranteed. According to a study done by developmental biologists, between 75–80% of embryos created through intercourse are naturally lost before they can become fetuses. This debate is not one that has a right or wrong answer, nor can it be clearly settled. Much of the ethical dilemma surrounding hESCs relies on individual beliefs about life and the potential for scientific advancement versus creating new human life.