Male and Female Orcs

[Nerwen]

The argument I have for Bolg son of Azog is that they were goblins. I think that goblins have a different origin than orcs, and they might breed differently.

No evidence for that, as far as I'm aware, but anyway "Bolg son of Azog" appears in a completed text published in Tolkien's lifetime– as "canonical" as it gets. (Meanwhile, "Azog the father of Bolg" shows up in the LoTR appendices.)

This, if not simply a hoax, as for all we know it may be, is merely one of Tolkien's numerous abortive retcons. He was given to sketching out radical changes to be made to his Legendarium, then abandoning them after a paragraph or two– often, no doubt, because it became clear they were unworkable. The many contradictory versions of the origin and nature of Orcs are a case in point.

Because of all this the "last known version is always the 'true' one" approach is very problematic indeed when applied to Tolkien's writing. The man was quite capable of suddenly jotting down on the back of an envelope:

Originally Posted by J.R.R.Tolkien, in an as yet unpublished manuscript

Elven 'horses' in truth more nearly resembled unicorns. This was of course well known to Aragorn, who showed no surprise at Asfaloth's horn. Frodo's failure to remark on it is harder to explain, but may be attributed to his limited power of observation..."

[skip spence]

That's curious, I wonder if that text is from the same collection that I stumbled upon when digging through the vaults of Oxford University last spring. This little gem contained some pretty revolutionary stuff regarding the relationship of Morgoth and Hurin:

Originally Posted by Originally Posted by J.R.R.Tolkien, in an as yet unpublished manuscript

...and Hurin [having escaped from his prison cell] grabbed a sword from the fallen guard and made his way up towards the surface of the mountain. Stealthily he made his way through the many halls and tunnels, ever upwards, until finally he saw a glimmer of the light of day through a high passage gate, and his heart leaped with joy. But alas, as he made his final steps towards freedom the doors shut with a heavy clang and darkness fell once again. In front of Hurin towered Morgoth himself, ironclad, armed with a great sword, Silmarils ablaze on his iron crown.
But Hurin the Steadfast was not daunted, there was a fierce rage flaming in his chest and with a terrible war-cry he hewed with his sword, intending to strike down his enemy. The two blades met with a bang, and the room was lit up by thousands of red and white sparks shooting through the air, and as the shadows returned so verily the two remained, in a stalemate, sword to sword.

Morgoth then spoke:
"Good, good, anger it the path to the Dark Side!"
"I'll never join the Dark Side! I will never join you!!" Hurin yelled.
"But there is something you don't know", said Morgoth, more quietly this time. "Hurin, I am your father!"
...