Social interactions can alter gene expression in the brain, and vice versa.
A critical insight came in 1992, in a study of songbirds led by David Clayton. He and his colleagues found that expression of a specific gene increases in the forebrain of a zebra finch or canary just after it hears a new song from a male of the same species.
…This may explain, in a very roundabout way, why I began rounding my vowels shortly after moving to Canada. (And why my maid of honour punched me in the arm when I said “about” wrong.)