Or just stubborness and ignorance? I have more than one family member who could totally do this, and not all of them are religious anti vaxxers or are diagnose

Or just stubborness and ignorance? I have more than one family member who could totally do this, and not all of them are religious anti vaxxers or are diagnosed as mentally ill or anything. In fact, I am a little surprised so many HNers see this behavior as unusual.