NomosLogic
Why Genetic Systems Don’t Collapse: Rethinking Causality in Complex Traits
Back to Blog
deterministic convergencedeterministic convergence biologydeterministic convergence genomicsdeterministic convergence systems biologydeterministic convergence geneticsdistributed genetic architecturedistributed causality geneticsmulti-variant interaction networksepistasis networksconstraint-based biologysystems-level genetics genomicinteraction modeling complex trait architecturepolygenic systems biologyevolutionary simulationgenomics fitness landscapemodeling convergence in evolutionary systemssimulation-based genomicscomputational genomics systems biologymodeling reproducible biological systemsbeyond GWASwhy GWAS failscorrelation vs causation geneticsinstability in genetic modelscorrelation vs causation genetics

Why Genetic Systems Don’t Collapse: Rethinking Causality in Complex Traits

Matt HardyMarch 25, 20262 min read

Editorial

For decades, the dominant paradigm in genomics has been implicitly simple: identify the variants most strongly associated with a trait, and you are closer to identifying its cause.

But this assumption carries a hidden expectation — that biological systems are, at some level, reducible. That removing the most influential component should degrade or collapse the system’s behavior.

What if that assumption is wrong?


The problem: instability disguised as insight

Many current approaches to complex trait analysis rely on probabilistic or statistical association. While powerful, these methods often exhibit instability:

  • Results vary across cohorts

  • Models shift with new data

  • Repeated analyses do not always yield consistent structures

If the underlying system is stable, why are our models not?


The observation: systems converge

In controlled simulation studies of genomic interaction networks, a different pattern emerges.

Across independent runs under identical conditions, systems repeatedly converge toward stable configurations of interacting variants. These configurations are not identical in composition, but they are consistent in structure and behavior.

This phenomenon can be described as deterministic convergence:

The reproducible emergence of stable interaction structures across independent simulations under identical conditions.


The critical test: perturbation

A key question follows:

If these systems are truly driven by dominant variants, what happens when those variants are removed?

The expectation under a traditional model is straightforward: disruption, degradation, or collapse.

But that is not what is observed.

Instead:

  • Systems continue to converge

  • Fitness landscapes reorganize

  • Previously lower-ranked variants rise to prominence

  • Overall system behavior is preserved

In some cases, convergence occurs more rapidly after perturbation.


The implication: causality is distributed

These observations suggest a different model of biological organization.

Rather than being governed by a small number of dominant causal variants, complex traits appear to be structured as distributed constraint systems:

  • Multiple variants contribute collectively

  • Stability arises from interaction patterns, not individual components

  • Apparent “dominance” reflects concentration, not necessity

When a highly influential variant is removed, the system does not fail — it reconfigures along alternative constraint pathways.


A shift in perspective

This has important implications.

If biological systems are distributed:

  • The question is not “which variant causes disease?”

  • But rather “how do interacting variants constrain the system toward stable outcomes?”

This reframing moves away from reductionist causality and toward system-level behavior.


Limits and scope

Not all biological systems are expected to exhibit deterministic convergence.

Some may remain:

  • highly context-dependent

  • multi-stable

  • or non-convergent under certain conditions

Distinguishing between convergent and non-convergent architectures becomes an important problem in itself.


Where this leads

If convergence is a real and generalizable property of biological systems, it suggests that we are not simply modeling biology — we are beginning to observe its underlying structure.

And that structure may be less about isolated causes, and more about constraints that shape possible outcomes.

MH

Matt Hardy

Published on March 25, 2026

For decades, the dominant paradigm in genomics has been implicitly simple: identify the variants most strongly associated with a trait, and you are closer to identifying its cause. But this assumption carries a hidden expectation — that biological systems are, at some level, reducible. That removing the most influential component should degrade or collapse the system’s behavior. What if that assumption is wrong?