There isn't a direct gene for ADHD or depression, but there is a 'sensitivity gene' that makes individuals more susceptible to stress. According to epigenetics, present and nurturing parenting in the first year of life can effectively neutralize the expression of this gene, preventing future mental illness.

Parenting isn't a one-way street. A child's inherent temperament (e.g., ADHD, agreeableness) actively shapes parental reactions. This creates powerful feedback loops where, for instance, a difficult child elicits stricter parenting, which in turn affects development. The outcome is often misattributed solely to the parenting style.

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.

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.

It's a myth that all cells are a 50/50 blend of parental DNA. Neuroscientist Catherine Dulac's work shows that entire brain areas can be genetically identical to either the mother or the father. This explains why certain behaviors and traits are so strongly inherited from one parent.

When sperm donor half-siblings meet as adults, they may feel attraction. This isn't an innate desire for kin, but a consequence of shared genes creating highly similar preferences. They seem like a "perfect match" because the usual childhood-developed sexual aversion is absent.

Trying to determine which traits you inherited from your parents is clouded by the 'noise' of shared environment and complex psychological relationships. For a more accurate assessment, skip a generation and analyze your four grandparents. The generational remove provides a cleaner, less biased signal of your genetic predispositions.