no it’s not precise, the combining of genes, but it gives you a good mathematical representation to predict this or that with some accuracy. And then you have to factor in the studies that find that an offsprings intelligence are calculated at approximately 60% from the maternal dna. Which is a good reason for men to pick intelligent women as mates.
But certainly, you don’t play with fire and make horrible breeding choices.
Now as for nurture, good luck. Throw trillions into education, and give ,” opportunities,” and not much is going to happen. initially there might be an increase of a few points, but over time there is a regression to the mean.When it comes to brains, you either have them or you don’t. It’s hardware. It’s a product of the protein-coding wrapped into the DNA
https://medlineplus.gov/genetics/understanding/traits/intelligence/
https://pmc.ncbi.nlm.nih.gov/articles/PMC5665562/
To say nurture does ‘not much’ is factually false. The global Flynn Effect proved that when nations built infrastructure, average national IQs surged by 30 points in a single century. Genetics cannot physically mutate that fast