---
_id: '64108'
abstract:
- lang: eng
  text: "<jats:title>Abstract</jats:title>\r\n                  <jats:p>We study how
    gene-environment interactions between education and genetic endowments affect
    cognition in old age and use this setting to show that – even with a valid instrument
    – two-stage least squares (2SLS) estimates of interaction effects can be far away
    from the true effect. This is the case when treatment effects are heterogeneous
    and compliance to the instrument depends on the interaction variable. We suggest
    estimating marginal treatment effects to address this problem. Our estimation
    results show complementarities between education and genetic predisposition in
    determining later-life memory. The marginal treatment effect estimates suggest
    substantially larger gene-environment interactions than the 2SLS estimates.</jats:p>"
article_number: ueag010
author:
- first_name: Johannes
  full_name: Hollenbach, Johannes
  id: '94632'
  last_name: Hollenbach
  orcid: 0009-0006-2008-0564
- first_name: Hendrik
  full_name: Schmitz, Hendrik
  id: '48879'
  last_name: Schmitz
- first_name: Matthias
  full_name: Westphal, Matthias
  last_name: Westphal
citation:
  ama: Hollenbach J, Schmitz H, Westphal M. Gene-environment interactions with essential
    heterogeneity. <i>The Economic Journal</i>. Published online 2026. doi:<a href="https://doi.org/10.1093/ej/ueag010">10.1093/ej/ueag010</a>
  apa: Hollenbach, J., Schmitz, H., &#38; Westphal, M. (2026). Gene-environment interactions
    with essential heterogeneity. <i>The Economic Journal</i>, Article ueag010. <a
    href="https://doi.org/10.1093/ej/ueag010">https://doi.org/10.1093/ej/ueag010</a>
  bibtex: '@article{Hollenbach_Schmitz_Westphal_2026, title={Gene-environment interactions
    with essential heterogeneity}, DOI={<a href="https://doi.org/10.1093/ej/ueag010">10.1093/ej/ueag010</a>},
    number={ueag010}, journal={The Economic Journal}, publisher={Oxford University
    Press (OUP)}, author={Hollenbach, Johannes and Schmitz, Hendrik and Westphal,
    Matthias}, year={2026} }'
  chicago: Hollenbach, Johannes, Hendrik Schmitz, and Matthias Westphal. “Gene-Environment
    Interactions with Essential Heterogeneity.” <i>The Economic Journal</i>, 2026.
    <a href="https://doi.org/10.1093/ej/ueag010">https://doi.org/10.1093/ej/ueag010</a>.
  ieee: 'J. Hollenbach, H. Schmitz, and M. Westphal, “Gene-environment interactions
    with essential heterogeneity,” <i>The Economic Journal</i>, Art. no. ueag010,
    2026, doi: <a href="https://doi.org/10.1093/ej/ueag010">10.1093/ej/ueag010</a>.'
  mla: Hollenbach, Johannes, et al. “Gene-Environment Interactions with Essential
    Heterogeneity.” <i>The Economic Journal</i>, ueag010, Oxford University Press
    (OUP), 2026, doi:<a href="https://doi.org/10.1093/ej/ueag010">10.1093/ej/ueag010</a>.
  short: J. Hollenbach, H. Schmitz, M. Westphal, The Economic Journal (2026).
date_created: 2026-02-11T09:20:49Z
date_updated: 2026-02-11T09:23:15Z
department:
- _id: '281'
- _id: '475'
doi: 10.1093/ej/ueag010
language:
- iso: eng
publication: The Economic Journal
publication_identifier:
  issn:
  - 0013-0133
  - 1468-0297
publication_status: published
publisher: Oxford University Press (OUP)
status: public
title: Gene-environment interactions with essential heterogeneity
type: journal_article
user_id: '37953'
year: '2026'
...