One of the reasons we decided that homeschooling might be a better fit for our son (now 10) was because he is so interested in the sciences, and school only offered one hour of science per week (He went to school through the first month of 2nd grade).
Now, he spends hours reading about science, exploring nature, setting up experiments, studying the periodic table of elements (sometimes he even takes it with him in the car :LOL ). We have several good physics, and chemistry books that he frequently pulls off the shelves. We subscribe to kid-oriented science magazines, which he devours, as well as National Geographic, which he reads as well. He spends lots of time watching Animal Planet, and the Discovery Channel (the history channel too - but that's another thread
). During the school year, he takes science workshops for homeschoolers, and we look for opportunities for him year round to explore his interests. He thinks Google is the best invention ever, because he has a whole world of knowledge literally right at his fingertips.
He spent a good chunk of this week standing in a creek pulling out bits of iron, and other rocks (geology is his fave), looking up facts about iron and other metals on Google, and studying his periodic table.
I don't personally know any grown unschoolers who've gone into the sciences, but I do know of at least onewho did: Thomas Edison!
And, if you have a budding scientist in your home, a book you might enjoy reading is "Curious Minds: How a Child Becomes a Scientist" edited by John Brockman. It's a collection of essays by scientists who describe their childhoods, and how their early experiences influenced (or not) their career choices. Maybe because we homeschool I was looking for their school stories, but I remember when reading it being struck by how little their elementary and high school schooling contributed to their interests. Most of them learned what really interested them outside of school, and then were able to pursue their passions once they got to college.
Hope this helps a bit!