It is common to worry about older family members
Social distancing measures are recommended due to a pandemic, which John is unknowingly carrying, and he sees his parents for the first time in months while wearing a face mask.
John wants to greet his parents.
John waves hello, but keeps his distance and keeps his mask on out of concern for his parents' health.
John runs up and gives his parents a big hug, stripping his mask off to give them each a kiss on the cheek.
John prevents his parents from catching any virus he's carrying.
John unknowingly gives both his parents a virus due to his lack of concern for their health.