Female mice can be turned lesbian by deleting a single gene at embryo stage

The simple procedure causes the modified mice to reject the advances of their male counterparts and attempt to mate with fellow females. Researchers found that disabling the FucM gene – which influences the levels of estrogen to which the brain is exposed – caused the mice to behave as if they were male as they grew up. The mutant female mice underwent a slightly altered developmental program in the brain to resemble the male brain in terms of sexual preference. By deleting the enzyme-producing gene, the scientists believe that they caused the female mice to be exposed to extra estrogen, by preventing their brains from filtering out the hormone.