How is it that mother-child relationships distribute across this four-way taxonomy? We don’t know. Genes are one candidate but the link to attachment — at least in infancy- is weak. This is not to say that genes don’t matter, they do. But their influence is mainly exerted in combination with the environment, like the mother’s attributes, the quality of partner relationships, and the amount of social support the parents receive. Genes are a double-edged sword: some genes help people get the most out of a warm and caring environment, whereas others accelerate the negative effects of inconsistent care. Scientists call this differential susceptibility and much research continues to understand better its effects.