Genetic technologies have been growing rapidly in sophistication and efficacy over recent decades, opening new avenues for humans to modify their own bodies and minds. It is possible that these technologies could allow the humans of today to sculpt entire lineages of their offspring and descendants, down through the generations. In this essay, I will first lay out three historic shifts in our understanding of what genes are and what they do. Then I will consider the long-term social, cultural, and moral implications of genetic interventions on human beings.