Common Risk Factors of Chronic Diseases

Twin brothers living in the same household have almost the same lifestyle. They eat the same food, exercise five times a week, and meditate regularly. However, the younger twin learned recently that he has been diagnosed with lung disease. Based on your readings and research so far, what could have contributed to this diagnosis? Provide in-text citation(s) to support your explanation.
Centers for Disease Control and Prevention (CDC). (2019, October 23). About Chronic Diseases. https://www.cdc.gov/chronicdisease/about/index.htm#:~:text=Chronic%20diseases%20are%20defined%20broadly,disability%20in%20the%20United%20States
Mayo Clinic. (2020). Infectious diseases. Retrieved from http://www.mayoclinic.org/diseases-conditions/infectious-diseases/home/ovc-20168649