Science be damned; to we norms, identical twins embody some dark form of magic. Spooked by their provocative flouting of laws of individuality, and fascinated by tales of their psychic connection, we know theirs is a bond forged in a realm beyond our ken.
Kim and Kelley Deal exemplify this eerie allure.
Even when we knew only of Kim, cornerstone and creator of gigantic bass lines in the Pixies, her self-possessed coolness put her in a category of her own.
When the pair joined forces as guitar-slinging doppelgangers in the Breeders, we at least had some answers to the riddle of Kim's outsider charm: She was in a relationship few experience and even fewer understand.
The Breeders, formed in 1990 by Kim and Throwing Muses' Tanya Donnelly, had a minor hit with debut LP Pod, an excellent album of (mainly) Deal songs that carried the signatures of both women's day bands.
Three years later, with Donnelly now busy with her own group, Belly, Kim threw a line to the sister she had last shared the stage with in a teenaged folk-rock outfit, the first to use the Breeders moniker.
Kelley would play lead guitar, never mind that she'd need to be taught how. More important was Kim's opportunity, with the acrimony of the Pixies' final year behind her, to be the real Deal writer/performer the Breeders allowed her to be.
Last Splash delivered on the promise of Pod, framing Kim's sweet-and-sour songs with powerfully surging alt-rock.
In Cannonball, the Breeders had an impossibly hooky pop track that bounced ahead on a wave of great ideas. Divine Hammer showed another side, smoother and sexier, a honey-dipped triumph of the Deals' combined voices but just one of several tracks that traded on that sisterly magic.
Patchy instrumentals aside, the rest of the album belted along with an energy that outshone the Pixies' post-Doolittle efforts and placed the Breeders at the vanguard of '90s indie-rock.
