Could some of the 12 Dwarves have been female?

[Earendil]

Coming back to the dwarves in The Hobbit: we know they all had beards, as Bilbo thinks he couldn't be mistaken for a dwarf due to his lack of beard. I feel pretty sure Tolkien's intention was that all Thorin's companions were male, but I don't think it would contradict anything he wrote if you decide that one or two were female. The closest thing to a definiitve statement is the mention in Appendix A that Thorin's sister Dís is "the only dwarf-woman named in these histories", but that could be chalked down to the hobbits making assumptions. I would think that if any of the others given in the family tree were female it might have been mentioned, but that still leaves six of Thorin's companions...

[Earendil]

I was wrong about one thing above, though. I said Tolkien didn't explain why dwarf-women don't travel much. In fact, he hints at the reason in The Lord of the Rings: "It is because of the fewness of women among them that the kind of the Dwarves increases slowly, and is in peril when they have no secure dwellings." Dwarf-women must be protected for the survival of the race, it seems, though it doesn't say whether dwarf-women approve of this arrangement. I suspect they do, by and large.

<snip>

This last hypothesis is bad news for female dwarf-adventurers, though, as it means they're not just queer and irresponsible folk, as other cultures deem adventurers; it means they're outright deviants and social rebels.

He does also say in Appendix A that many of the women don't marry. And I'm sure there's a statement somewhere (not in Appendix A) that they are never forced to marry. So I don't see any reason why a dwarf-woman who isn't planning to marry couldn't decide to go adventuring. Other dwarves might not approve, but while it would be more unusual than a male dwarven adventurer, it might not be seen as any more irresponsible.

That means dwarf-babies have beards, too!

Hairy little babies!