Scientists keep prying into the sex lives of Neanderthals. In the past decade, they’ve revealed that Neanderthals got busy with both Homo sapiens and Denisovans, another lineage of now-extinct humans.

But there’s more: Mounting evidence suggests Neanderthals also had a habit of inbreeding, or conceiving with close relatives. Several studies have now reported this based on genetic patterns and bone abnormalities thought to result from intra-family flings.

First, let’s review the facts b