SwedishMaskrosbarnDandelion child, someone who has a tough childhood and still turns out alright, like a dandelion breaking through asphalt.

Obviously this actually translates quite well, but doesn't seem to be commonly used in English. A couple of American child psychologists used it in a paper, and most online uses seems to refer to that, but it's been around in Swedish for decades. I think it's quite a striking image. http://www.theatlantic.com/magazine/archive/2009/12/the-science-of-success/307761/ - Article on the paper that introduced the term in English)