“不知不觉地沾染上”可以翻译为 “unconsciously pick up” 或 “inadvertently acquire” 。
“unconsciously pick up” 强调在无意识状态下获得、沾染上某种东西（如习惯、行为、疾病等） ，例如：He unconsciously picked up some bad habits from his friends.（他不知不觉地从朋友那儿沾染上了一些坏习惯。 ）
“inadvertently acquire” 同样表达非故意、不经意间获得，“inadvertently” 突出不经意、疏忽大意，“acquire” 表示获得、染上，例如：She inadvertently acquired a taste for spicy food during her trip.（她在旅行期间不知不觉地养成了吃辣食的习惯。 ）