A California-startup focused on genetically editing human embryos — a step toward creating so-called designer babies — is raising money as many of Silicon Valley’s ultra-rich turn their attention to one of the most controversial technologies in medicine.

Bootstrap Bio, created about 18 months ago, is working on technology to change the DNA in an embryo, according to two people familiar with the company and one of its investors. Altering those cells to make genetically modified children is intended to eliminate inherited diseases or enhance desirable traits, which can be passed on to future generations.