I've been reading "Circe" and it got me thinking: Circe's mother was a water nymph named Perse. Perse's parents were Oceanos and Tethys, who were both Titans. Why then is Perse a Nymph if both of her parents are Titans? I have some possible ideas but it's all just speculation.
Some further info is that Perse was one of 3,000 siblings. If you want to read what they have about her on Wikipedia, here's the link. https://en.m.wikipedia.org/wiki/Perse_(mythology)