Science teaches without reservation that life begins at conception. It is a scientific fact that an organism exists after conception that did not exist before conception. This new organism has its own DNA distinct from the mother and father, meaning that it is neither part of the mother nor part of father. As the embryo grows, it develops a heartbeat (22 days after conception), its own circulatory system, and its own organs. From conception it is a new organism that is alive and will continue to grow and develop as long as nutrition is provided and its life is not ended through violence or illness.
Keith L. Moore, is a world-renowned embryologist. Moore puts it plainly in Before We Are Born: Essentials of Embryology (7th edition, Philadelphia, PA: Saunders, 2008, p. 2): "[The zygote], formed by the union of an oocyte and a sperm, is the beginning of a new human being."
Here is an example from another scientific work.
From Human Embryology & Teratology (Ronan R. O’Rahilly, Fabiola Muller [New York: Wiley-Liss, 1996], 5-55): "Fertilization is an important landmark because, under ordinary circumstances, a new, genetically distinct human organism is thereby formed[.]"
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