Idea
The result is not the recipe
Two plants may differ in height because of their genes, the light they received, or how their genes affect their response to light. Height alone cannot tell you which explanation fits. You need to compare their genes and growing conditions.
Botanist Wilhelm Johannsen distinguished observed traits from inherited makeup. Modern genetics studies how genes and environments produce those traits.
Different heights do not necessarily mean different genes.
Where it breaks down
Some traits have a strong relationship to particular genetic variants. The distinction does not imply that all traits are equally changeable or that genetic influences are unimportant.
How it connects
Genes and conditions can produce similar visible differences through different routes.
This idea appeared in What you see is an outcome, the Involves connection for November 2, 2026, which asked: Why doesn't a visible difference tell you what caused it?
Check yourself
Two plants have different heights. What follows from that observation alone?
Their phenotypes differ, but the cause is not yet established. Exactly. Different outcomes can reflect inheritance, environment, or their interaction.
What the sources establish
Observable traits alone do not uniquely identify the contributions of genetic makeup and environment.
Sources
Phenotype (National Human Genome Research Institute), Definition and narration: observable traits, genotype, and environment