On Monday travelling home from Perth to Melbourne with my wife and toddler son, we were denied boarding by the check-in agent at Qantas domestic after presenting our printed itinerary and my lifetime gold qantas frequent flyer card, my wife tried to present her Silver Qantas frequent flyer card but we were abruptly and rudely told that we must present photo identification for all 3 of us including our 23 month old son. As I did not have any photo identification for my son we were denied boarding. When I said to the check-in man that I was sure we don't need photo identification for my baby and I would be complaining about this, the check-in man accused me of threatening him and he said we would not be flying at all today. We were not given boarding passes, were forced to miss our flight and finally was given boarding passes some 90 minutes later after intervention by a duty manager, who could have let us boarding our scheduled flight but denied us boarding, however he did let us fly some 5 hours later due to alleged threats the agent claimed I made, which I denied making. I tried several times to apologise to the check-in agent if he was offended by anything I said, but he refused to accept my apology and stormed off leaving us abandoned at business check in. I have asked Qantas for apologies from the 3 people involved in this business class check-in failure and clarification of documents required for check in for adults and children.