Dad is 65 and I'm 35. Every year I come to visit my parents, dad seems to know less about how computers work. He has used MS-DOS, Norton Utilities and every Windows version since Windows 3.0, yet here I am, explaining to him how a tree view in a file browser works. Such a tree view existed in the File Manager in Windows 3.x, in Norton Commander and in TREE.EXE for MS-DOS, but he has forgotten about them all, together with what he did or said 15 minutes ago. It feels like he's aging fast.