Abstract Background Familial aggregation of Barrett's esophagus (BE) and esophageal adenocarcinoma (EA) suggests a genetic pattern in fewer than 10% of patients with the former diseases. In 1983, BE was described in identical twins, underlining the hereditary influence on the development of mucosal dysplasia in some patients with this epithelial alteration. At present, some studies have attempted to identify chromosomal alterations among patients with familial aggregation of BE or EA, but there is not a clear pattern. Methods Description of the case report of a male patient who underwent esophagectomy due to EA on a long BE, who had a monozygotic twin without gastroesophageal reflux symptoms and no upper GI endoscopies before. Results A 53-year-old man was diagnosed with EA and a long BE (8 cm length) in 2017. He underwent CROSS neoadjuvant treatment and minimally invasive Ivor-Lewis esophagectomy. The pathological report indicated a GI T3N1M0 adenocarcinoma. Unfortunately, the patient developed lung metastases and passed away in 2019. Before that, the patient recalled that he had an identical twin brother with no gastroesophageal reflux symptoms, but we decided to scope him in 2017. The gastroscopy report revealed a 2 cm hiatal hernia with a long BE (C4M6 Prague Classification) but with no dysplasia. Nowadays, the twin patient is under close follow-up with proton pump inhibitors (PPI) and has not developed dysplasia. Conclusion Monozygotic twins provide a perfect model to study the possible influence of genetic predisposition to develop BE and EA. The development of EA in a patient guided us to diagnose and treat a long BE in his asymptomatic identical twin. More studies should be done to find the possible genetic alterations linked to familial aggregation of BE and EA.