Does intelligence come from your genetics or your environment? Thanks to experiments on identical twins, we have known for a while now that the answer is both, with genetics accounting for about half of a person's intelligence, and environmental factors accounting for the other half.

But scientists have been largely unable to determine which specific genes affect intelligence--until now. A scientific team led by Danielle Posthuma, geneticist at Vrije (Free) University in Amsterdam has reviewed genetic data from about 80,000 adults and children, and found 52 genes that have a direct impact on intelligence. Twelve of these were already known to science, but the other 40 are brand new discoveries. It's an enormous breakthrough in a field of study where successes have been few.

That's great--but what exactly does this discovery mean for you and me? Here's some of what we now know:

1. Intelligence is even more complex than we thought.

The 52 genes in the new study only account for only about 5 percent of intelligence, suggesting that there may be thousands of genes that play a part in cognitive function. Even with genetic info from 80,000 subjects, geneticists are just getting started tracking down intelligence-related genes. For one thing, the researchers chose to limit their study to people of European descent because the same genes sometimes have different effects in people from different ethnic groups. So it's an understatement to say that there's a lot of research left to be done.

2. Non-smokers may be smarter.

Or maybe it's that smarter people don't smoke. Either way, some of the gene variations associated with higher intelligence are likelier to also appear in people who have never smoked. Others are found in people who once smoked but succeeded in quitting.

3. We may be able to help children learn better.

How can this research be used? It's too early to know for certain, but one scientist involved with the study suggested that understanding how genetic variations affect intelligence would make it easier to measure different strategies and treatments intended to boost brain power. That might make it easier to help children develop their intelligence, and possibly even help the elderly retain more of their cognitive function later in life.

4. There are plenty of things we should be doing right now.

Environment is as important a factor in intelligence as genetics, the scientists note, and we already know quite a bit about how a person's environment can affect his or her intelligence. That means there are lots of things we can and should be doing right now to help boost people's mental function. High on the list would be eliminating lead from the environment, especially from contact with children, since it's known to reduce intelligence. Making sure to add iodine to children's diets, if they're not getting much of it in their food, is another known way to improve intelligence. Reducing exposure to pollution, ensuring proper pre-natal care, and good nutrition throughout your life are all good ways to keep your intelligence level high, the scientists noted.

It will probably be a long wait before we can pop an intelligence-boosting pill before taking a test or starting a writing project. In the meantime, paying attention to environmental factors really can make a big difference.