Conception is the fusion of two gametes: one male cell (sperm) and one female cell (egg).
These gametes fuse to create an embryo as a result of mating in organisms that procreate sexually. Each gamete contributes 50% of the parent's DNA. As a result of this fertilization the embryo, with a 50% DNA contribution from each parent creates a unique offspring. Shortly after the formation of the embryo, the embryo begins to grow and differentiate eventually becoming a fetus.