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Huh, I did a blog post about this just last night. Basically, people's personality has an impact on whether they have kids, personality is heritable, fertility

Huh, I did a blog post about this just last night. Basically, people's personality has an impact on whether they have kids, personality is heritable, fertility won't be low forever given current conditions but who knows how conditions will change. http://hopefullyintersting.blogspot.com/2018/05/falling-fertility-rates-shouldnt-be.html http://hopefullyintersting.blogspot.com/2018/05/falling-fert...

Analemma_ 8y ago
> Basically, people's personality has an impact on whether they have kids, Maybe you address in your post, but as stated this doesn't make a lot of sense. Fertility is falling across all demographics and in all developed countries and has been for decades – are you saying everybody everywhere has experienced a personality shift over that time? And while fertility probably does have some genetic component, I think that's a small piece of it compared to prevailing economic conditions (having kids is friggin expensive and this generation is deeply in debt) and social mores (whether there's powerful religions pressure to have kids). Genetics neither explains this nor provides a way out of it.
- rossdavidh 8y ago
  Well presumably until you get to a certain level of development, the only personality trait that matters is whether you want to have sex or not, but after that point (relatively recently in generational terms) other factors matter. Kind of like how height is mostly determined by food availability, until you get to a point when sufficient food is available for everyone, and then genetic factors matter more.
- Symmetry 8y ago
  No, I'm saying that both personality and material conditions have an effect on who has children. Or it might be that the personality traits that cause people to have children in 21st century America are different than those that caused people to have children in 19th century America. But in any event the traits that seem to cause people to have more children in current US conditions are substantially heritable. How many generations will it take? Quite possibly a lot but it'll happen eventually baring further external shocks. And there are lots of other factors involved as well. I think the differences in fertility between Germany and France are particularly illustrative.
gerbilly 8y ago
> Basically, people's personality has an impact on whether they have kids Sounds like a tautology to me. If this were true wouldn't that mean that the genes for the heritable part of the "want to have kids" personality type would be overrepresented in the population, because they came from parents who had kids?
- Symmetry 8y ago
  Because to the extent that there is a "wanting to have kids" trait directly it was less necessary in the ancestral environment because there was also a "wanting to have sex" trait that could do the work. But getting into the stuff we actually measure, stuff like Agreeableness[1] that makes people want to have more kids in the modern world also has significant drawbacks if there's the danger of, e.g., starving to death if you don't look out for number one. [1]https://en.wikipedia.org/wiki/Agreeableness https://en.wikipedia.org/wiki/Agreeableness

Analemma_ 8y ago

> Basically, people's personality has an impact on whether they have kids, Maybe you address in your post, but as stated this doesn't make a lot of sense. Fertility is falling across all demographics and in all developed countries and has been for decades – are you saying everybody everywhere has experienced a personality shift over that time? And while fertility probably does have some genetic component, I think that's a small piece of it compared to prevailing economic conditions (having kids is friggin expensive and this generation is deeply in debt) and social mores (whether there's powerful religions pressure to have kids). Genetics neither explains this nor provides a way out of it.

rossdavidh 8y ago
Well presumably until you get to a certain level of development, the only personality trait that matters is whether you want to have sex or not, but after that point (relatively recently in generational terms) other factors matter. Kind of like how height is mostly determined by food availability, until you get to a point when sufficient food is available for everyone, and then genetic factors matter more.
Symmetry 8y ago
No, I'm saying that both personality and material conditions have an effect on who has children. Or it might be that the personality traits that cause people to have children in 21st century America are different than those that caused people to have children in 19th century America. But in any event the traits that seem to cause people to have more children in current US conditions are substantially heritable. How many generations will it take? Quite possibly a lot but it'll happen eventually baring further external shocks. And there are lots of other factors involved as well. I think the differences in fertility between Germany and France are particularly illustrative.

gerbilly 8y ago

> Basically, people's personality has an impact on whether they have kids Sounds like a tautology to me. If this were true wouldn't that mean that the genes for the heritable part of the "want to have kids" personality type would be overrepresented in the population, because they came from parents who had kids?

Symmetry 8y ago
Because to the extent that there is a "wanting to have kids" trait directly it was less necessary in the ancestral environment because there was also a "wanting to have sex" trait that could do the work. But getting into the stuff we actually measure, stuff like Agreeableness[1] that makes people want to have more kids in the modern world also has significant drawbacks if there's the danger of, e.g., starving to death if you don't look out for number one. [1]https://en.wikipedia.org/wiki/Agreeableness https://en.wikipedia.org/wiki/Agreeableness