Ok, I need the birth rates of fantasy races. (context included)

[Belac93]

I need the birth rates of the races in 5e D&D. Most specifically Goliaths. The other races would be nice too, but Goliaths are the most.

Now, for the context.

So, my characters have made it their goal to adopt children. One of the children they adopted had an older sister, about 15-16.

Here is where it gets weird.

She is a bit of a...Womanizer (for men). They rescued her from barbarian forest gnomes, and she immediately attempted to seduce the barbarian fighter.

Part of the lore in my world, that I told my players about beforehand, was that any player race can have children with any other. The race of the child will randomly be one of the parent races or a mixed race.

So, I assumed that the goliath would be able to avoid it easily. He had pretty good will. Then she proceeded to roll a 20, while he rolled a 4. They proceeded to [censored].

Now, she is pregnant. I need to know how likely it is for the child to be a boy or a girl. Like, a percentage chance.

And other races would be helpful too. Knowing my players, I'll probably need them.

[Cglied]

Humans in Real World industrialized nations give birth to males around 51% of the time. My guess is that this is some evolutionary process that gives our species the best chance of survival.

As for Humans in a fantasy setting, or Goliath's, elves, dwarves, etc. for that matter I suspect you're free to interpret the biological imperatives that dictate these rates for yourself.

Also? Creepy.

[Hrugner]

The natural sex ratio of all sexually reproducing creatures is very near 1:1. There are several explanations as to why, but a 50/50 shot is close enough.

There's a few factors that tilt that ratio. Poor diet and stress seem to be tied to spontaneous abortion of male fetuses. Younger fathers tend to produce more male children as well. These aren't huge differences though, maybe 1-2% each.

Here's a handy map of sex ratios by country
http://chartsbin.com/view/2337

Haldane's rule should come into play here though. Haldane notes that in hybrid species, females are most likely to suffer hybrid dysfunction. Females are more often either non-viable offspring or sterile, than male hybrids.

That should be enough info to get an idea of what's best here.

[Bladeyeoman]

The natural sex ratio of all sexually reproducing creatures is very near 1:1. There are several explanations as to why, but a 50/50 shot is close enough.


I'd have to check one of my books, but I think that generally evolution leads to sex ratio balances out to have approximately 1:1 ratio of the sexes *at sexual maturity*. So if you have a race where you think one or the other genders has high mortality before having children - say, many young males die in battle before finding a woman - then over time the race will start to skew the ratio in favor of the high-mortality gender. I think. (I believe this is why sex ratios for humans in industrial nations very slightly favor males).

Of course, if you feel like it, you can provide an alternative to genetically determined genders. For many species of amphibians and reptiles, males and females are genetically indistinguishable, and gender is determined by the temperature experienced by the developing embryo. So if you wanted to add some exotic mythobiology, you could decide that for some of your races, the gender of a child depends on some factor experienced by the mother during pregnancy (perhaps exposure to magic? cycle of the moon? food eaten? Whatever you want!)

EDIT: Oooh, I'm really liking the idea of Genasi variety of a hybrid offspring depending on the conditions (physical, magical, emotional - not sure) experienced by the pregnant mother.

[Bladeyeoman]

Haldane's rule should come into play here though. Haldane notes that in hybrid species, females are most likely to suffer hybrid dysfunction. Females are more often either non-viable offspring or sterile, than male hybrids.

I had forgotten the specifics of Haldane's rule, so refreshed on it. I think you've got it backwards, at least for humans. Haldane found that generally heterogametes (having two different sex chromosomes, which in humans is the male with XY) are more likely to suffer from sterility.

How much biology you want to include is entirely up to you, but in all birds and some reptiles, females are heterogametes. So, if you're applying this idea, you might choose a high rate of sterility for hybrid males of most races, but for dragonborn, Aarakocra, and any other reptilian or avian races, have the hybrid females have a higher chance of sterility.

Of course, we're talking offspring of races in a magical world, so whatever rules you want are fine. If it were me, I'd probably keep it simple.

[Regitnui]

The longer the adults of a race live, the fewer children they'll generally have. This isn't biological, but just an explanation why elves haven't overrun the world.

[Belac93]

Ok, I think I got it. Goliaths will be able to mate 10% of the time with most races, 50% with half humans, 70% with humans, and 85% of time with other Goliaths. Male birth rates will be 2% higher than female.

For the elf thing, its gonna be really low. Elves will be able to mate with most races 1% of the time, 5% with humans, 10% with half-elves, and 12% with elves of a different subrace, and 15% with other elves.

[Regitnui]

Ok, I think I got it. Goliaths will be able to mate 10% of the time with most races, 50% with half humans, 70% with humans, and 85% of time with other Goliaths. Male birth rates will be 2% higher than female.

For the elf thing, its gonna be really low. Elves will be able to mate with most races 1% of the time, 5% with humans, 10% with half-elves, and 12% with elves of a different subrace, and 15% with other elves.

How'd you calculate that?

[Belac93]

How'd you calculate that?

I didn't. Where I am, I believe it was about 11 PM when I posted that, and its 1:30 AM now. And I've been playing D&D since 7, with a break for dinner and fresh air. I'm really just pulling numbers out of my portable hole right now.

[Regitnui]

I didn't. Where I am, I believe it was about 11 PM when I posted that, and its 1:30 AM now. And I've been playing D&D since 7, with a break for dinner and fresh air. I'm really just pulling numbers out of my portable hole right now.

Information in, Dice rolls out. So runs the DM machine.

[Hrugner]

I had forgotten the specifics of Haldane's rule, so refreshed on it. I think you've got it backwards, at least for humans. Haldane found that generally heterogametes (having two different sex chromosomes, which in humans is the male with XY) are more likely to suffer from sterility.

How much biology you want to include is entirely up to you, but in all birds and some reptiles, females are heterogametes. So, if you're applying this idea, you might choose a high rate of sterility for hybrid males of most races, but for dragonborn, Aarakocra, and any other reptilian or avian races, have the hybrid females have a higher chance of sterility.

Of course, we're talking offspring of races in a magical world, so whatever rules you want are fine. If it were me, I'd probably keep it simple.

That's what I get for checking the original source and not reading far enough along.


Many observers have noted that the crossing of different animal
species produces an offspring one sex of which is rare or absent, or if
present sterile, whilst occasionally the missing sex is represented by
intermediate forms. Doncaster(1) conclnded that the missing sex was
generally thc female, bnt, as will be shown later, this is by no means
always the case.

He then goes on to explain that this observation became the norm due to birds being the most tested in hybridizing, and them being the counterexample.

Thank you for pointing out my error.