i never thought about that and now that you made me think about this, do even aliens have a gender? :O
if they do, would they have two? what if they reproduce between the participation of 3 or 4 genders? :O how it would be like?
and answering your question, well for me i always imagined him as a boy x'd. i don't know why.
Depends on the alien and what kind of world they evolved on I guess? And the multiple parents thing is probably possible too because see above? :D
Whatever you make of them is probably not wrong XD