It makes sense that there could be some from all of them (based on my limited knowledge of Amphibiosans) with Zoidberg exiting after Fry and Zapp, I'd assume that neither of them are involved... unless Zoidberg was too.
Kryten mentioned that Zoidberg wasn't on the bridge of the space canoe when it experienced explosive decompression. Zapp, Leela, Fry and Amy were the only DNA carrying creatures in contact with Kif.
Sure hope Bender's RNA wasn't involved.
Bender's "Robo RNA" should have no effect on Kif's reproduction.
However, if Bender gave a firstborn from Kif's batch of tadpoles to the Robot Devil, it would open up a lot of questions.