Lots of young EAs are struggling with the issue of whether, when, where, and how to have kids, and whether becoming a parent will undermine being an Effective Altruist, in terms of opportunities costs such as career, time, energy, money, focus, and values.
For whatever it's worth, I'm happy to answer any questions you might have about parenting -- its pros and cons, ethics, practicalities, etc.
Background: I'm a 57-year-old dad; I've raised a 26-year-old daughter and a 6-month-old baby. I've also helped raise a teenage step-son, and I come from a big, close-knit family (I have about 30 cousins.) I've lived as a parent in the US (mostly), UK, and Australia. I'm also a psychology professor who's taught courses on parenting-relevant topics such as behavior genetics, educational psychology, evolutionary psychology, human intelligence, evolutionary game theory, and decision making. I've been involved in EA for the last 6 years, and I have a pronatalist orientation, with an interest in population ethics, reproductive bioethics, gamete donation, and cognitive and moral enhancement. I'm not an expert on every practical or scientific issue about parenting, but maybe my perspective could be useful to some EAs.
This is a fair point. My older daughter (now 26) was very smart, and easily bored in normal public school. We worked very hard to be able to send her to the best private schools we could find, from age 8 onwards (she ended up at Westminster School in London, then Oxford). She might have also flourished if homeschooled, if we'd had the time to do that.
So, Caplan's data might not apply so clearly if you and your partner are above about IQ 130 or 140, which means your kids are likely to be close to that (there is regression to the mean, but it's fairly limited for IQ, which has a heritability in adults of about 70-80%). However, Caplan does address this point in the education book.
I would argue that if you have smart kids, try to find the most selective schools you can that embrace standardized testing and streaming, and that have gifted programs, honors classes, etc. Smart kids love having peers who are smart -- and even if it doesn't make all that much different to their eventual career success, it can be a huge benefit to their day-to-day life quality and sentient experience.
I agree that EAs should support a lot more experimentation in parenting and education, especially in nurturing exceptional talent! I think we are nowhere near optimal in our current educational approaches.