Within-family effect of ancestry on complex traits in a Mexican population.

Within-family analysis reveals significant Indigenous American ancestry effects on height and type 2 diabetes in a Mexican population, with effects comparable to population-level estimates.

• Why it matters: Understanding genetic contributions to complex traits is challenging due to environmental confounding and biases in population comparisons, limiting insights into true genetic effects.
• What they did: Researchers analyzed genetic data from 52,583 unrelated individuals and 39,714 relatives across 17,627 families in Mexico City, estimating within-family ancestry effects on 15 traits.
• The result: They found notable within-family effects of Indigenous American ancestry on height and type 2 diabetes, supporting genetic influence, while no within-family effects were observed for educational attainment, highlighting environmental or confounding factors.