In 1974 he and fellow pupil Paul Fitzpatrick won the Scottish Daily Express schools debating competition.

[5] In 2021, a talk by Clark, titled "For Whom the Bell Curve Tolls: A Lineage of 400,000 Individuals 1750-2020 Shows Genetics Determines Most Social Outcomes", was cancelled due to accusations of promoting eugenics.

[6][7][8] Clark’s argument for the relationship between wealth and reproductive success in A Farewell to Alms has been criticized for its lack of empirical support.

Critics argue that his emphasis on heritability risks downplaying structural factors that perpetuate inequality, such as racism, sexism, and class-based discrimination.

Many scholars contend that interventions in education, healthcare, and housing can significantly affect individuals and communities, even if the impacts are not immediately visible across generations.