That same raspberry bush, in better soil with more sunlight and a homeowner who actually thought to sprinkle it with some water once in a while, might thrive. There might be a flowing crop of raspberries coming from the bush with many more crops to come. It would be properly pruned and probably covered as the winter months approach. THAT is nurture.
It's entirely possible The Little Raspberry Bush That Could is just really tough, the kind of plant that can make it in spite of neglect. I bet there's some people like that, too. It's equally possible it won't make it through the winter and I'll find myself buying a new raspberry bush next year. Which is fine, when we're talking about a plant. I think you'll all be relieved to know I take a far less laissez-faire approach to raising my child.
Can you make a kid born lacking intelligence a genius with the right parenting? No, but you can make things easier for them academically with lots of love and support. Can you make a child dealt an unfortunate hand in the looks department prettier? No, but you can make them feel beautiful on the inside, and that will show on the outside to the right people. You can't make a basketball star out of a really short kid or a quarterback out of one that can't throw, but you can make a person that tries really hard. Like plants, you can't change the stuff people are made of, but you can still give them the right conditions to grow.