Devas and their appearance Far as i know Devas are born without parents so why are they in two genders?

If they have no biological need to reproduce what is the reason for two genders and if the Devas are born after doing many good and noble things in this world, how are their companions and concubines are born, are they residing in a world inhabited by other beings?
Reproduction is not the only function of having opposite genders. If that is the case, both males and females should look the same when sexual organs are covered. Even at the beginning(Agganna sutta) of man kind, reproduction happened as a result of beings who looked different getting attracted to the differences.

Companion nymphs are beings who get born in heavens due to less powerful karma. Their main duty is to entertain the Deva who owns them.