Eugenics is the belief that humanity can be perfected through genetic manipulation

Complex traits come from twin studies that assumed that identical twins and fraternal twins would differ only by the amount of shared DNA

Thus, identical twins are more likely to share the same hobbies, eat the same foods, and run in the same social circles than fraternal twins

A more recently appreciated influencer of heritable traits is the microbiome, the term for all of the microorganisms (bacteria, fungi and viruses) that peacefully co-exist with humans

From a genetic standpoint, your human genes are probably outnumbered over 100 to 1 by microbial genes

The microbial influence can be passed from mother to child during and possibly before birth, but remains partially sensitive to diet

The microbiome can even influence your epigenetics. Researchers are just beginning to tap into the potential of microbial treatments for diseases

While properly conducted gene therapy does offer real hope for curing rare genetic diseases, its limitations stop well short of sci-fi