Experiments with the mutagenic Terrigen Mist (a process known as Terrigenesis) gave them various powers, but caused lasting genetic damage and deformities, which led to a long-term selective breeding program in an attempt to mitigate the effects of these mutations. The Terrigen Mist is a natural mutagen, arising as a vapor from the Terrigen ... More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.