Summary: Thanks to medical advances, grandparents become their own grandchildren.
My parents told me they wanted to live on through their grandchildren, but I always misinterpreted their meaning. I became an ectogenesis researcher, developing the first reliable generation of artificial human exowombs.
As biotech advanced, exowombs were used to grow brain-dead clones for spare parts. The procedure was fairly simple, and aging could be artificially controlled, so a year old, artificially sustained clone body might be a functional adult. I commissioned clones for my parents. They floated in life-support tubes, waiting the day they'd be needed.
It was fortunate the paramedics got both right after the car accident. Their bodies were ruined beyond repair, but not their minds. Grafting the brains into cloned bodies was still a novel procedure, but it was still their only chance. So, we transplanted each of their brains into their waiting clones, which were identical to their teenage selves.
They've since made an almost full recovery, save in one way. I am now their legal guardian until they re-reach legal adulthood. Now, I understand how much of a nightmare I was as a teenager. I am just going to opt for a cyborg body next time.