Of all the papist arguments presented for why Jesus is the only child of Mary (i.e. his brothers were cousins, his brothers were step brothers from Joseph’s previous marriage), most of these are not particularly convincing. One argument, however, that does seem to at least bring up a valid question is that if Mary had other sons besides Jesus, then why would he have asked John to care for her after his death? Would not his brothers be responsible for this? Just curious as to your thoughts.