My mother is ninety, but that hasn't diminished her interest in all things medical. After talking about 23andMe, she was sent scurrying around the house for old hair brushes. I now have a collection of her hair and some cheek swabs, packaged and ready to be lodged in my safe at home
Twenty years time, when whole-genome sequencing costs five pounds, one of her descendants may be interested in analysing this particular ancestor .. or cloning her!
Is it reassuring to have your complete genome on file? In principle you could be cloned in future. That person would be your "future-twin" .. and so immortality beckons.
I don't know: does a twin feel the other twin is a version of themselves? I rather suspect not.