Education: The longer time a person spends in school, the more likely they’ll see a boost in IQ. (Twelve years of mandatory education is more intense and rigorous mind training experience than a couple of hours on a video game.) Analyses have found evidence that each additional year in school adds 3.7 IQ points.
Nutrition and environment: Good nutrition might not boost IQ, but it’s believed that poor nutrition and toxins (lead, in particular) in a child’s environment does decrease it. Iodine deficiencies during development are believed to decrease IQ by around 10 points.
Time: The world is getting smarter every year. Really. Mean IQ scores appear to be increasing between 2 and 3 points per decade. It’s called the Flynn effect, and it is likely the result of increasing quality of childhood nutrition, health care, and education.
Well heck, stupid is as stupid does.