There are actually companies that have a policy like this so that time off is granted to long-term employees who do not have children, while using the same time

There are actually companies that have a policy like this so that time off is granted to long-term employees who do not have children, while using the same time off as additional maternity/paternity leave people can "use early" (& above the state-mandated 2 weeks of parental leave) if life circumstances end up with them having a child earlier. I know this because I run one such company and helped develop the policy -- the company is http://parse.ly http://parse.ly btw :) We call it a "sabbatical", and it is five weeks of paid leave, meant to be used all at once after 4 years at the company, or used early by parents when they have children. The Etsy policy of 26 weeks is certainly generous but honestly quite difficult for a small startup to offer. A big company like Etsy has a much smaller probability that several people on leave at the same time means an "entire department" is no longer staffed, whereas that would be a real possibility on our small team. We want to be fair to parents and non-parents alike, but we have to keep the lights on!