I've actually taken that test a few times over a few years. One thing they do with IQ scores is taking age into account to normalize everything more, and I believe the result I posted was from a time two years prior to the post, when I was 13. That also happened to be around the time that I took school far less seriously than I should have, which had negative consequences many years later. In later times, I got higher scores by more than 20 points I believe. In some ways, this is more of a score of the combination of how much you've exercised your intelligence, or however you want to say that, with your intelligence.
One idea behind the IQ test is that you have a set base intelligence, which would learn more towards it being genetics. But as far as I am aware, it has not been linked to genetics solely. It's another of those areas where people argue nature vs. nurture, though in this case I personally think it's obviously both, and that genetics do play a large role in intelligence, or at least the desire to learn certain things, which is why siblings (like my sister and I) can be so different even if they are raised similarly with the idea that they should do well in school and learn a lot, and so on.
There's a bunch to this topic, and I think Booyah posted a link to somewhere with a bunch of information on IQ tests, or at least he had a long post, I forget which.