Jack, it sounds like the only person you offended....was yourself! :)

I didn't realise you had health history with your kids. Sometimes realisation and perspective can hit you like a brick wall and I get that. But don't double/triple check your humour. One thing I've always been proud of in Australian culture is we like to take the piss out of ourselves and we (in the past) have known that even if we're not being PC there is no offence intended (or taken!) and it's all in good fun. I know times are changing, but that's the Australia I grew up in and love.