Just like vinegar—mine was given me 30 years ago and was 75 years old at the time and is now…well, 105 years old, give or take. The ‘mother’ is still part of the original mother but then again, if the hammer head is changed and then the baton is changed to fit the hammerhead, is it the same hammer? My “mother” is actually the same, traveling many miles in many countries to be in my cave here in France. I would love to know more about your sourdoughs starters.