# Day 3 **URL:** https://isgw-forum.colorado.edu/c/isg-workshops-2026/day-3/32.md [Latest](https://isgw-forum.colorado.edu/latest.md) · [Categories](https://isgw-forum.colorado.edu/categories.md) · [Tags](https://isgw-forum.colorado.edu/tags.md) --- ## [About the Day 3 category](https://isgw-forum.colorado.edu/t/about-the-day-3-category/743)
**Author:** [@JML](https://isgw-forum.colorado.edu/u/JML)\ **Replies:** 0\ **Last updated:** [May 26, 2026, 5:10pm UTC](https://isgw-forum.colorado.edu/t/about-the-day-3-category/743 "2026-05-26T17:10:06Z")
heritability, variance components, matrix approaches, IBD vs IBS, family and twin modeling --- ## [RCode for doing biometric moderation?](https://isgw-forum.colorado.edu/t/rcode-for-doing-biometric-moderation/883)
**Author:** [@jense180](https://isgw-forum.colorado.edu/u/jense180)\ **Replies:** 1\ **Last updated:** [June 10, 2026, 8:37pm UTC](https://isgw-forum.colorado.edu/t/rcode-for-doing-biometric-moderation/883 "2026-06-10T20:37:04Z")
I am interested in testing whether a biometric moderation model in which genetic influences on personality vary as a function of relationship satisfaction provides a better fit to the data than a model without moderation… --- ## [Bivariate twin model when bh^2 is large but rg is low](https://isgw-forum.colorado.edu/t/bivariate-twin-model-when-bh-2-is-large-but-rg-is-low/838)
**Author:** [@kristen](https://isgw-forum.colorado.edu/u/kristen)\ **Replies:** 0\ **Last updated:** [June 10, 2026, 3:54am UTC](https://isgw-forum.colorado.edu/t/bivariate-twin-model-when-bh-2-is-large-but-rg-is-low/838 "2026-06-10T03:54:09Z")
In the part 4 video, it mentions that if bh^2 is high but rg is low, that means genes play a large role in the overlap between the two traits but the genetic influences are trait-specific. I am having a hard time wrappi… --- ## [How do you know when translate and use "+" and " \* "](https://isgw-forum.colorado.edu/t/how-do-you-know-when-translate-and-use-and/788)
**Author:** [@anonymous](https://isgw-forum.colorado.edu/u/anonymous)\ **Replies:** 3\ **Last updated:** [June 5, 2026, 1:45pm UTC](https://isgw-forum.colorado.edu/t/how-do-you-know-when-translate-and-use-and/788 "2026-06-05T13:45:30Z")
When translating equations into path analysis models and vice versa - how do you know when translate and use “+” and " \* " - so for example where the is mean = SNP\*b1 + b0 in slide 13 of the lectures slides given before … --- ## [When should I use ADE instead of ACE?](https://isgw-forum.colorado.edu/t/when-should-i-use-ade-instead-of-ace/790)
**Author:** [@anonymous](https://isgw-forum.colorado.edu/u/anonymous)\ **Replies:** 7\ **Last updated:** [June 5, 2026, 1:41pm UTC](https://isgw-forum.colorado.edu/t/when-should-i-use-ade-instead-of-ace/790 "2026-06-05T13:41:52Z")
When should I use ADE instead of ACE? --- ## [Knowing the actual relatedness of DZ twins doesn’t contribute much to your estimation of ACE](https://isgw-forum.colorado.edu/t/knowing-the-actual-relatedness-of-dz-twins-doesn-t-contribute-much-to-your-estimation-of-ace/792)
**Author:** [@anonymous](https://isgw-forum.colorado.edu/u/anonymous)\ **Replies:** 20\ **Last updated:** [June 5, 2026, 1:36pm UTC](https://isgw-forum.colorado.edu/t/knowing-the-actual-relatedness-of-dz-twins-doesn-t-contribute-much-to-your-estimation-of-ace/792 "2026-06-05T13:36:05Z")
Is the takeaway that knowing the actual relatedness of DZ twins doesn’t contribute much to your estimation of ACE model parameters vs. estimating the relatedness at .5 if you have both MZ and DZ twins in your model? --- ## [Definition of Environmental components in Twin Modeling](https://isgw-forum.colorado.edu/t/definition-of-environmental-components-in-twin-modeling/793)
**Author:** [@emiliana.tonini](https://isgw-forum.colorado.edu/u/emiliana.tonini)\ **Replies:** 2\ **Last updated:** [June 5, 2026, 1:29pm UTC](https://isgw-forum.colorado.edu/t/definition-of-environmental-components-in-twin-modeling/793 "2026-06-05T13:29:13Z")
Hi all, Thank you for a great session! I am wondering how should we understand “environmental components” in twin modeling ? It is basically referring to anything that is not genetic? And is it referring to a specific … --- ## [Do DZs always share 1/4 of Dominant variance?](https://isgw-forum.colorado.edu/t/do-dzs-always-share-1-4-of-dominant-variance/787)
**Author:** [@anonymous](https://isgw-forum.colorado.edu/u/anonymous)\ **Replies:** 2\ **Last updated:** [June 4, 2026, 9:05pm UTC](https://isgw-forum.colorado.edu/t/do-dzs-always-share-1-4-of-dominant-variance/787 "2026-06-04T21:05:07Z")
Do DZs always share 1/4 of Dominant variance? --- ## [Can you explain the comparison of the saturated to the ACE model again?](https://isgw-forum.colorado.edu/t/can-you-explain-the-comparison-of-the-saturated-to-the-ace-model-again/789)
**Author:** [@anonymous](https://isgw-forum.colorado.edu/u/anonymous)\ **Replies:** 2\ **Last updated:** [June 4, 2026, 8:42pm UTC](https://isgw-forum.colorado.edu/t/can-you-explain-the-comparison-of-the-saturated-to-the-ace-model-again/789 "2026-06-04T20:42:58Z")
Can you explain the comparison of the saturated to the ACE model again? --- ## [What does the dominance term tell us when traits are highly polygenic?](https://isgw-forum.colorado.edu/t/what-does-the-dominance-term-tell-us-when-traits-are-highly-polygenic/796)
**Author:** [@kristen](https://isgw-forum.colorado.edu/u/kristen)\ **Replies:** 1\ **Last updated:** [June 4, 2026, 8:31pm UTC](https://isgw-forum.colorado.edu/t/what-does-the-dominance-term-tell-us-when-traits-are-highly-polygenic/796 "2026-06-04T20:31:57Z")
Dominance is often described as something that occurs within a locus, eg. a non-linear difference in the trait for AA, Aa, and aa genotypes. But when we fit an ADE model for a highly-polygenic trait with thousands of lo… --- ## [Effects of violating twin model assumptions (GxE, assortment, etc.)?](https://isgw-forum.colorado.edu/t/effects-of-violating-twin-model-assumptions-gxe-assortment-etc/795)
**Author:** [@kristen](https://isgw-forum.colorado.edu/u/kristen)\ **Replies:** 2\ **Last updated:** [June 4, 2026, 8:05pm UTC](https://isgw-forum.colorado.edu/t/effects-of-violating-twin-model-assumptions-gxe-assortment-etc/795 "2026-06-04T20:05:39Z")
In the second day 3 video, it mentions several assumptions of the classical twin design (random mating, no GE correlation, no GxE interaction) that could be difficult to test. If any of these assumption violations are p… --- ## [C versus D](https://isgw-forum.colorado.edu/t/c-versus-d/797)
**Author:** [@albenar](https://isgw-forum.colorado.edu/u/albenar)\ **Replies:** 1\ **Last updated:** [June 4, 2026, 5:44pm UTC](https://isgw-forum.colorado.edu/t/c-versus-d/797 "2026-06-04T17:44:37Z")
Why are C and D negatively confounded? --- ## [Definition variables](https://isgw-forum.colorado.edu/t/definition-variables/794)
**Author:** [@kristen](https://isgw-forum.colorado.edu/u/kristen)\ **Replies:** 0\ **Last updated:** [June 4, 2026, 2:45am UTC](https://isgw-forum.colorado.edu/t/definition-variables/794 "2026-06-04T02:45:44Z")
I had a few questions about definition variables related to different Day 3 videos. I’m moving them to their own separate thread here because it seems like a big enough topic to need a thread to itself. The questions I … --- ## [What would the goodness of fit statistics look like for a scenario where the E model was preferable to the ADE model?](https://isgw-forum.colorado.edu/t/what-would-the-goodness-of-fit-statistics-look-like-for-a-scenario-where-the-e-model-was-preferable-to-the-ade-model/791)
**Author:** [@anonymous](https://isgw-forum.colorado.edu/u/anonymous)\ **Replies:** 3\ **Last updated:** [June 3, 2026, 8:27pm UTC](https://isgw-forum.colorado.edu/t/what-would-the-goodness-of-fit-statistics-look-like-for-a-scenario-where-the-e-model-was-preferable-to-the-ade-model/791 "2026-06-03T20:27:12Z")
What would the goodness of fit statistics look like for a scenario where the E model was preferable to the ADE model? --- ## [Are male MZ twins more genetically similar than female MZ twins](https://isgw-forum.colorado.edu/t/are-male-mz-twins-more-genetically-similar-than-female-mz-twins/786)
**Author:** [@anonymous](https://isgw-forum.colorado.edu/u/anonymous)\ **Replies:** 2\ **Last updated:** [June 3, 2026, 8:21pm UTC](https://isgw-forum.colorado.edu/t/are-male-mz-twins-more-genetically-similar-than-female-mz-twins/786 "2026-06-03T20:21:58Z")
Are male MZ twins more genetically similar than female MZ twins due to Barr body inactivation of the X chromosome creating a sort of cellular mosaicism regarding the X chromosome between female MZ twins? Is this included… --- ## [If we want more covariates, do we add rows or more code?](https://isgw-forum.colorado.edu/t/if-we-want-more-covariates-do-we-add-rows-or-more-code/785)
**Author:** [@anonymous](https://isgw-forum.colorado.edu/u/anonymous)\ **Replies:** 8\ **Last updated:** [June 3, 2026, 8:20pm UTC](https://isgw-forum.colorado.edu/t/if-we-want-more-covariates-do-we-add-rows-or-more-code/785 "2026-06-03T20:20:59Z")
If we want more covariates, do we add rows or more code? Or I mean more lines of code? --- ## [How do you choose starting values for OpenMx models?](https://isgw-forum.colorado.edu/t/how-do-you-choose-starting-values-for-openmx-models/784)
**Author:** [@anonymous](https://isgw-forum.colorado.edu/u/anonymous)\ **Replies:** 4\ **Last updated:** [June 3, 2026, 8:14pm UTC](https://isgw-forum.colorado.edu/t/how-do-you-choose-starting-values-for-openmx-models/784 "2026-06-03T20:14:47Z")
How do you choose starting values for OpenMx models? --- ## [Questions on twin modelling](https://isgw-forum.colorado.edu/t/questions-on-twin-modelling/776)
**Author:** [@dmitrk02](https://isgw-forum.colorado.edu/u/dmitrk02)\ **Replies:** 0\ **Last updated:** [June 3, 2026, 11:08am UTC](https://isgw-forum.colorado.edu/t/questions-on-twin-modelling/776 "2026-06-03T11:08:57Z")
First of all, thank you for the great updated lecture on the classical twin design! It was very helpful, and the way Hermine Maes confidently introduced the models’ syntax gives the hope that we can do it ourselves. A c… --- ## [Questions about the third day 3 video](https://isgw-forum.colorado.edu/t/questions-about-the-third-day-3-video/773)
**Author:** [@kristen](https://isgw-forum.colorado.edu/u/kristen)\ **Replies:** 0\ **Last updated:** [June 3, 2026, 6:19am UTC](https://isgw-forum.colorado.edu/t/questions-about-the-third-day-3-video/773 "2026-06-03T06:19:29Z")
Edit: Most of my questions in this post were answered during the tutorial. I am including the answers as I think I understand them below, plus one remaining question I’m still confused about at the bottom. Questions tha… --- ## [Questions about the second day 3 video](https://isgw-forum.colorado.edu/t/questions-about-the-second-day-3-video/772)
**Author:** [@kristen](https://isgw-forum.colorado.edu/u/kristen)\ **Replies:** 0\ **Last updated:** [June 3, 2026, 3:29am UTC](https://isgw-forum.colorado.edu/t/questions-about-the-second-day-3-video/772 "2026-06-03T03:29:00Z")
I have some questions about the second Day 3 video, “Estimate heritability using data from relatives/twins”: On slide 28 (roughly 19:34 in the video), it compares saturated and constrained models. How can a constrained… --- ## [Questions about the first day 3 video](https://isgw-forum.colorado.edu/t/questions-about-the-first-day-3-video/771)
**Author:** [@kristen](https://isgw-forum.colorado.edu/u/kristen)\ **Replies:** 0\ **Last updated:** [June 3, 2026, 2:16am UTC](https://isgw-forum.colorado.edu/t/questions-about-the-first-day-3-video/771 "2026-06-03T02:16:59Z")
Hi! I’ll be a student in Day 3 session B, and I have several questions about the material. I thought I’d ask them here ahead of time so I don’t slow things down asking too many questions in the tutorial. The questions …