All living things on earth have DNA, a marvelous molecule which has produced untold millions of species which inhabit every corner of the globe. The question of where life came from - whether it develooped on earth or came from space - is really quite silly, because we are "space" as much as space is. Everything "out there" is also "here", and vice versa. Organic molecules are formed naturally on Earth, but we are also showered by meteorites which carry organics. Add to this the discovery that the Orion Nebula is an "organic-molecule factory", producing "precursors to life-enabling molecules", and you have a space broth of pre-biotics seeding other worlds. Assuming that the Orion Nebula is no the only organic factory out there, one can only conclude that life is common and ubiquitous. And if this mix of conditions, over billions of years, produced the most adaptable molecule for life on Earth, why would we think that it would be otherwise on other planets?