FORTUNE: The social media site will give gender-neutral paid leave for up to 20 weeks starting May 1.
Other companies that have embraced such policies include Etsy, Facebook, and Change.org. The rationale? Family structures have changed, and allowing for more evenly distributed parenting equals happier employees, both male and female (within, of course, both heterosexual and same-sex couples).
“The goal of this change was to expand how we think about parental leave,” says Jeffrey Siminoff, Twitter’s newly-appointed VP of inclusion and diversity (the exec joined the company from Apple about eight weeks ago). “Primary caregiving is something that’s hard to define.”