In the giant-collision scenario, computer simulations suggest that the moon had two parents: Earth and a hypothetical planetary body called “Theia” but a comparative analysis of titanium from the moon, Earth and meteorites indicates the moon’s material came from Earth alone.
If two objects had given rise to the moon, “Just like in humans, the moon would have inherited some of the material from the Earth and some of the material from the impactor, approximately half and half,” said Nicolas Dauphas, associate professor in geophysical sciences at UChicago, and co-author of the study. “What we found is that the child does not look any different compared to the Earth. It’s a child with only one parent, as far as we can tell.”
Odd. To me, the parent and child look nothing alike.