Since Sir Francis Galton coined the phrase “nature versus nurture” 150 years ago, the debate about what makes us who we are has dominated the human sciences.

Do genes determine our destiny, as the hereditarians would say? Or do we enter the world as blank slates, formed only by what we encounter in our homes and beyond? What started as an intellectual debate quickly expanded to whatever anyone wanted it to mean, invoked in arguments about everything from free will to race to inequality to whether public policy can, or should, level the playing field.

Today, however, a new realm of science is poised to upend the debate — not by declaring victory for one side or the other, nor even by calling a tie, but rather by revealing they were never in opposition in the first place. Through this new vantage, nature and nurture are not even entirely distinguishable, because genes and environment don’t operate in isolation; they influence each other and to a very real degree even create each other.

The new field is called sociogenomics, a fusion of behavioral science and genetics that I have been closely involved with for over a decade. Though the field is still in its infancy, its philosophical implications are staggering. It has the potential to rewrite a great deal of what we think we know about who we are and how we got that way. For all the talk of someday engineering our chromosomes and the science-fiction fantasy of designer babies flooding our preschools, this is the real paradigm shift, and it’s already underway.

Genes, it turns out, don’t affect who we become just on their own, inside our bodies — they work, in part, by shaping the environments we seek out or engender.

Picture a kid who is born with two working copies of what’s known as the sprinter’s gene, ACTN3. By elementary school she might be winning every game of tag, every race, and be chosen first whenever sides are drawn up. You could see how parents and coaches might encourage a kid like that to join an organized sports team and how she would be likely to receive positive feedback for her performance on it, which in turn might motivate her to train harder. By high school she makes varsity track and soccer, and the more she excels, the more coaching and training is made available to her.