It is amazing what academia spends millions of dollars to confirm. Please read this article. Among the results is that language is learned in social interactions and that we as humans are wired to acquire language.
I have spent the last 15 years of my career working as an applied linguist, teaching language acquisition to others and help others acquire languages such as Arabic, Farsi and Pashto. Using the right strategies and methods I found out that you can help anyone, repeat anyone, acquire a new language starting at level 1 to level 3 (ILR-Interagency Language Roundtable) within a period ranging from 4 weeks (40 hrs/week) for level one to 24 weeks (600 hours) for level 3.
Despite of my proven bone fide results the unbelievers are plenty and the most common objection I hear is that aptitude matters and that some people just cannot do it. These fallacies are propagated by myth makers and academics who usually do not want to do the work needed to help their students acquire a new language. One big reason academics cannot do the work is that they excel at teaching 'about' a language rather than teaching the language. The key to my success is that I have put together a business process for language acquisition where you can turn ANY native speaker of the language into a very efficient language instructor and produces uniform results. These results are replicable across languages as long as the process is followed.