# Transmission of human handedness: a reanalysis

## TL;DR

This paper reanalyzes how human handedness is influenced by genetics and culture, finding stronger maternal effects and providing an open-source model for further study.

## Contribution

The study introduces an extended gene-culture co-evolutionary model with improved methodology and sex-specific transmission effects.

## Key findings

- Accounting for criterion shifts improves model fit and parameter estimation accuracy.
- Maternal effects on handedness are stronger than paternal effects.
- Daughters show greater sensitivity to maternal effects than sons.

## Abstract

Human handedness results from the interplay of genetic and cultural influences. A gene-culture co-evolutionary model for handedness was introduced by Laland et al. (1995), and this study generalizes that model and the related analysis. We address ambiguities in the original methodology, particularly regarding maximum-likelihood estimation, and incorporate sex differences in cultural transmission. By fitting this extended framework to existing familial and twin datasets, we demonstrate that accounting for criterion shifts significantly improves model fit and parameter estimation accuracy. We find stronger maternal than paternal effects on handedness, with daughters exhibiting greater sensitivity to these effects than sons. We provide an open-source Python implementation of the model, which is a robust platform for comparing gene-culture models and applying them to diverse datasets.