Kidults? Oh God no, that is shocking . I usually refer to mine as the kids, though they're both in their 40's!
And I am Nana, because my own mum was, as was her mum and so on back through the generations. My kids called my MiL 'Nanny' to differentiate between the two of us, and this has carried through to my DS's family, where his boys call me us Nana and Grandpa, and their other GP's Nanny and Granddad.
Kate Garroway-Care at home costs