Mana all three of my kids have had a stage lasting months, or even years, of calling my husband and I by first names, usually starting between one or two years old. I've always been surprised when people freaked out about it "She called you firstname!!" "Yep, that's my name..." I don't understand the fuss. They all still call us Mum and Dad, or some variation of such, at least some of the time. But even if they didn't and only used our names I still wouldn't fuss... Maybe that's weird of me?