Photosynthesis takes in light.
planets are studied with spectrograph to receive specific ranges of light that represents the type of material the body is made of.
To see light is to receive light.
if there is a photosynthesis-like phenomenon in human [mammal?] biology at work, then the light absorbed at the time of birth very well could have a physical influence on the person.
Astrology could really be a defined structure of this effect.