Proven: We're Extraterrestrial

That's what they're saying:

Martins and her colleagues said they discovered uracil and xanthine, which are precursors to the molecules that make up DNA and RNA and are known as nucleobases in rock fragments of the Murchison meteorite, which crashed in Australia in 1969. She explained that “early life may have adopted nucleobases from meteoritic fragments for use in genetic coding which enabled them to pass on their successful features to subsequent generations."

Image of xanthine molecule structure from Wikimedia Commons