This alien "seeding" theory of the Earth has been touched on in numerous science fiction films including PROMETHEUS(2012) and MISSION TO MARS(2000). In fact, an older Hammer movie called Quatermass And The Pit(1967 - aka "Five Million Years To Earth") touches on alien tampering with the Earth: in this particular movie insectoid Martian aliens resembling oversized grasshoppers have purportedly performed genetic experiments on Earth primates resulting in, of course humans!
As an agnostic I've not only struggled with the notion of religion and the existence of God but also the question "where do I come from?" Did I evolve from primates through a natural process of evolution? Or something else entirely?