Hydrogen comes from Water that is split apart in Stage 1
The process by which eggs are made is called Fertilization, when the egg cell meets the sperm cell and form a zygote.
I believe that present day was a theory that became a evolution developed because it was a historical event involved
Liquid water, which is necessary for life as we know it, continues to exist on the surface of Earth because the planet is at a distance, known as the habitable zone, far enough from the Sun that it does not lose its water to the runaway greenhouse effect.