This article maybe explains why my grandfather would get so angry when us cousins would ask him to speak in Italian, his childhood language, when we were small.

This article maybe explains why my grandfather would get so angry when us cousins would ask him to speak in Italian, his childhood language, when we were small. We thought it was so neat that he had this whole other world, but at most he would say a few words for us, then lapse into a stony silence. In later years he wouldn't even say the few words. We all knew he wasn't mad at us, but he was definitely angry, definitely upset, maybe somehow embarrassed too - but why? As kids we'd think, maybe he's getting forgetful in his old age. In fact his mind was tack sharp until his final year, in his 90s. I had no idea there was a name for this. But it makes a lot more sense now.