Why is the idea that behaviour is either completely innate or completely learned too simple?

The idea that animal behaviour is either strictly innate or entirely learned is considered too simple by modern biologists because it relies on a false dichotomy. In reality, all behaviours emerge from a complex, continuous interaction between an animal's genes and the environment in which those genes are expressed.12

This interaction is fundamental for several reasons:

• Genetic Predisposition for Learning: Rather than being independent of genetics, learning is often "instinctive." Animals are frequently genetically predisposed to acquire specific types of information that were crucial to the survival of their ancestors. For example, honeybees are biologically programmed to learn the colours and odours of flowers only at specific times during the foraging process.13
• Environmental Influence on Gene Expression: Environmental factors—such as nutrition, social interactions, and hormonal exposure—can influence how genes are activated and subsequently shape behaviour. For instance, the aggressive behaviour of mice is influenced by both genetic factors and early-life experiences, such as maternal handling or social isolation.24
• Adaptive Limits: The "general-purpose" view of learning, which assumed animals could learn anything with equal ease, has been replaced by the understanding that learning abilities are adaptively specialized. Animals are shaped by their experiences, but the interpretation of those experiences is governed by rules set by their genes.3

Ultimately, behaviour is not the result of "blind instinct" nor simply the product of experience, but rather the outcome of a sophisticated interplay between inherited material and the environment.23