The women of this matrilineal society shun marriage and raise their kids in homes with their entire extended families—but no dads.

Men of the Mosuo, who live around Lugu Lake on the border between Yunnan and Sichuan Provinces, do help to raise kids—just not their own, with whom the men typically have only limited relationships.

Instead the men help look after all the children born to their own sisters, aunts, and other women of the family.

In the unique Mosuo tradition called the walking marriage, women invite men to visit their rooms at night—and to leave in the morning.

Women may also change partners as often as they like, and promiscuity carries no social stigma.

In fact, most Mosuo women don't change walking-marriage partners very frequently. And they rarely carry on more than one romantic relationship at a time.