When is it too late to learn another language? It is never too late to learn another language; adults quite advanced in years have learned to speak another tongue. However, recent research indicates that there seems to be a "window of opportunity" during which the brain is particularly receptive to learning language. Children above the age of 7 have a much harder time learning a new language, and may never reach the level of fluency that a native speaker acquires. Which is more influential, genetics or environment? This is one of those thorny issues that keeps coming up, but has no definitive answer. There is plenty of evidence that indicates that children are born with genetically-determined temperaments that shape a child's response to the world. However, it is also the case that these traits in turn change the way the world responds to them, creating an endless feedback loop. For example, aggression is a trait with a strong genetic component. Yet aggressive children tend to elicit rejection from their peers. This creates a social environment that gives rise to even more aggression. How can we separate out a lifetime of differential treatment from the influence of genes? We have to content ourselves with the answer that both play an important role, and that the relationship between the two is complex. | 
2002 McGraw-Hill Higher Education