Final answer:
Forty-niners were distinguished by their arrival in California in 1849, participation in the gold rush, and pursuit of fortune through mining; being born in California is not a characteristic that differentiates them from non-miners.
Step-by-step explanation:
The one characteristic that does not differentiate a Forty-niner from non-miners is being born in California. Forty-niners were the prospectors who traveled to California in 1849 during the California Gold Rush, but their place of birth was not relevant to their activities or identity as miners.
The term 'Forty-niners' refers specifically to those individuals who arrived in California in 1849, were motivated by the opportunity to find gold, and sought their fortune through mining. However, being born in California does not distinguish Forty-niners from anyone else during that historical time, as people from numerous locations, both domestic and international, became known as Forty-niners if they participated in the Gold Rush. Participation in the gold rush and seeking fortune through mining are distinguishing factors, while the year of arrival is directly tied to the nickname 'Forty-niner.'