|The sexual background of Halford is a far better topic.|
To reduce it to absurdity ...
DM: All right, this setting is a fantasy version of medieval Europe. You can choose your national background, or roll.
Player 1: I'll roll ... hey, I'm Irish ... and with Viking ancestry! The blood of the Lochlannach flows in my veins!
Player 2: Yeah, you know that means a Viking raped your mom, right?
Player 1: Excuse me?
Player 2: What do you think, they asked for her hand in marriage? I'm sorry, but it's just a fact of medieval life. Your character is a bastard conceived by force.
DM: That's not necessarily true. The Viking blood could have come from an earlier generation ...
Player 2: Who still got raped. I don't know why you're acting so shocked at these natural facts that are necessarily part of the setting.
Player 1: I dunno. Do I have to ...
Player 2: Yes. It's historical canon!
DM: Player 2, what kind of GM did you play under before that gave you the impression it was OK to act this way?
Player 2: Someone who didn't knuckle under to the political correctness brigade. Hey, my own character was a product of rape due to the setting and I handled it all right.
DM: Do tell ...
Player 2: You see, logic demands that evil creatures can only reproduce through the most evil kind of sex there is. My backstory called for my father to be a necromancer and my mother an anti-paladin. They had no alternative but to rape each other.
All: They what?
Player 2: It happens. Charm spells were involved in this case. You see ...
DM: Okay, okay, let's move on.
For those completely bereft of imagination, and who don't want to make a stand on a dubious setting detail that's about as productive as random ass-boils, here are six other ways half-orcs can come into being while keeping orcs evil.
1. Humans sometimes seek out orcish partners out of decadence and perversity.
2. The orc is the most evil race there is. Those who actively promote evil willingly breed with orcs on ideological grounds.
3. Humans are not born orcs, but become that way through mutation or evil deeds. A half-orc is one who has willingly or otherwise arrested his or her orcish development.
4. Half-orcs are artificially bred by test-tube wizards.
5. Inbreeding leads to half-orcism. Inbred half-orcs in the past produced full-orcs.
6. Half-orcs are part of the normal genetic variation of orcs - they happen to look sufficiently human, if ugly, to "pass" in human communities. Likewise, there are very ugly humans who can "pass" as half-orcs.