The effect of a good caregiving environment is not to make siblings more similar, but to increase their variability by allowing diverse traits to flourish. This challenges the foundation of twin studies, where a lack of correlation between siblings is often interpreted as a lack of environmental influence.

Ideologies that rely on a 'blank slate' view of human nature have made a catastrophic error. As genetic technologies become mainstream, the public is forced to confront the tangible reality of genetic predispositions in their own reproductive choices. This will unravel the blank slate worldview, a cornerstone of some progressive thought.

While designed to reward merit, China's Gaokao system favors the wealthy. Families in elite districts or those who can afford expensive private tutoring have a significant advantage, perpetuating inequality rather than providing a level playing field for all students.

People tend to marry and befriend those who are genetically similar, a process that amplifies genetic inequality in the next generation. This is compounded by geographic sorting, where individuals with genetic propensities for success migrate away from disadvantaged areas, leaving them 'doubly disadvantaged, genetically and environmentally.'

The Polygenic Index (PGI) summarizes thousands of minor genetic effects into a single predictive score for complex outcomes like educational attainment or heart disease. This 'age of genomic prediction' will radically alter social domains like insurance, education, and even embryo selection, creating profound ethical challenges.

Attributing traits to either genetics or environment is a false dichotomy. As the genetic disorder PKU shows, outcomes depend on the *interaction* between the two. Believing a trait is purely "in our genes" wrongly dismisses the power of environmental interventions, which can completely alter outcomes.

A study by sociologist Emma Zhang found an older sibling's arbitrary academic advantage (from being old for their grade) boosts the younger sibling's performance. This demonstrates a powerful non-genetic, non-parental mechanism through which family-level advantages compound and perpetuate broader societal inequality.

Your outcomes are influenced not just by your own DNA but by the genes of those in your social environment, a concept called 'genetic nurture.' A spouse’s genes can affect your likelihood of depression, and a child's genes can evoke specific parenting behaviors, showing that the effect of genes doesn't stop at our own skin.

The massive investment gap in education ($75k/year at elite private schools vs. $15k at average public schools) creates an insurmountable advantage for the wealthy. This financial disparity, which translates to a 370-point SAT gap, is a more powerful determinant of future success than individual character or talent.