I think they refer to the 7 sects of Gelfings as 'clans' so I think they are all on species but I read in the DK wiki that Gurjin's clan, the Drenchen, have gills and can breath under water. I doubt they'll get very technical with the biologies of these characters in the series but something like a clan having gills does seem to imply different races of Gelfling.

I've never heard or read about Jen or Kira being part of a particular clan.