There is a theory called ‘early childhood determinism’ — the idea that experiences in the earliest stages of life have a disproportionately large and lasting impact on personality.
I do not fully accept this theory. But it points to a deeper pattern: in the fastest-developing phase of any system, the influence of external environment is amplified many times over, and tends to become fixed in some form.
This pattern has abundant support in biology. A plant’s phototropism is strongest at germination. An animal’s behavioral patterns are most easily shaped in early life. The plasticity of the nervous system peaks during early development.
Human beings are no exception.
From embryo to the period just after birth, a human being passes through the most rapid and critical phase of development in their entire life. The foundational settings of the nervous system, the endocrine system, and the circadian rhythm are all established within this window. There is no reason to assume that the climate environment during this period — temperature, light, seasonal rhythm — leaves no trace on a life form in the midst of high-speed development.
Two Everyday Observations
Consider two familiar experiences.
On a bright, sunny afternoon, people feel lighter, more open. On a winter morning, people burrow deeper into their covers and resist getting up. For an adult, these are passing moods — they dissipate within the hour.
But for a rapidly developing infant, the situation may be entirely different.
The same changes in light, the same temperature signals — acting on a nervous system not yet fully formed, exquisitely sensitive to external stimuli — may not produce a transient reaction at all. They may be encoded into the baseline of development, becoming part of the temperamental tendencies that persist throughout life.
A Concrete Example: Winter
Winter means extremely low energy input — sparse light, temperatures near their annual low. Under these conditions, the survival pressure facing any biological organism converges on a single imperative: minimize heat exchange with the outside world, draw energy inward, core it.
This is a survival strategy, not a personality judgment.
But when this strategy becomes the developmental backdrop for a life form’s first months of existence, it may leave corresponding traces at the level of temperament: strong boundaries, inward energy, low desire, cool rationality.
This is what people often describe when they describe Aquarius. It was not the stars that shaped the Aquarian temperament. It was the light and temperature of winter — leaving similar traces on those born into that season.