Papers · Articles

— Omxus Press

A. C. Applebee, L. N. Combe · 2026

Abstract

Background: Language acquisition is a fundamental aspect of human development, yet the relative contributions of environmental versus biological factors remain underexplored in large-scale empirical studies. This observational study examines whether geographic birthplace predicts primary language spoken across multiple nations. Methods: We analysed national census data from eight countries (N = 1,811,487,320 individuals) spanning six continents. The primary outcome was concordance between country of residence and dominant national language spoken. Chi-square goodness-of-fit tests and e!ect size calculations (Cohen’s h) were conducted. Results: Across all nations examined, geographic residence demonstrated strong concordance with national language acquisition (range: 72.0%–96.9%). E!ect sizes ranged from h = 0.46 to h = 1.22 (mean = 0.93; classified as “medium” to “large” by conventional standards). The observed pattern held regardless of the specific language examined. Conclusions: Geographic environment appears to be an extraordinarily strong predictor of language acquisition. Supplementary analysis of international adoption studies and twin research confirms that environment, not genetics, determines which language an individual speaks. The implications for understanding human behavioural acquisition more broadly warrant further investigation.

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