어도 알다

can tell without being told

Says that some other route to the knowledge was unnecessary. Three lines are about speech: 누구라고 말 안 해도 알 정도로 나랑 닮은 얼굴로 'so like me you wouldn't have to be told', 말씀 안 하셔도 알겠고 'you don't have to say it.' The rest run on seeing, and 딱 봐도 알겠어 'you can tell at a glance' is worth keeping as a phrase: 초콜렛은 딱 봐도 알겠어, 볶음밥 수준이 어떨지 안 먹어봐도 알겠다.