Because most pronunciation and word choices were based on region the notion that linguistics are determined by nurture rather than nature is supported
Harvard conducted a dialect study that determined where test participants were most likely from based on the words they used or pronunciations of certain words.
When the study was originally conducted by Bert Vaux and Scott Golder, over 350,000 survey responses to certain words and pronunciations were cataloged to pinpoint where certain pronunciation's location was.
When someone else takes the test his or hers responses are cataloged with the region where the word or pronunciation is most commonly used when the survey was first taken.
My own responses determined I was most likely from the northeast around Pennsylvania, New Jersey, or New York, I was born in Philadelphia and lived in Pennsylvania until I was 9.
Had language been shaped by nature i would use a lot of words from Virginia, because my Mother has lived most of her life in Fred Vegas.