Pickman's model
Starry Wisdom
Groundbreaking use of CRISPR selects sex of mice with 100% efficiency
Researchers at Francis Crick Institute and the University of Kent have used the CRISPR gene-editing system to produce litters of mice that are 100 percent either male or female. The technique could help prevent the unnecessary culling of animals of unwanted sex in agriculture or scientific…
newatlas.com
so at the moment they're only doing this with mice but it doesn't take much to suggest that this might find a use in those parts of the world where a boy, for example, is perceived as the more desirable offspring