Sisters Sam and Syd K go viral on TikTok for incredible “Blood Harmony” singing

Theo Salaun
samkandsydk tiktok sisters

Music TikTok has found a new obsession: Sisters Sam and Syd Kendall, who go by ‘samkandsydk.’ Covering songs from Keane and Fleetwood Mac, the duo are teaching the internet what “blood harmony” means.

A “harmony” is essentially when sounds blend together simultaneously in a way that produces a pleasing effect for listeners. In the music world, a “blood harmony” is one of the rarer forms of harmony – and one that is only produced by siblings (hence the “blood” mention).

In an interview with Rolling Stone, Billie Eilish’s brother, Finneas, describes “blood harmony” as “an English expression for what it sounds like when siblings sing together, that biologic chemistry.”

This expression was probably not very familiar to the TikTok world, until sisters Sam and Syd Kendall came around. With two videos posted in the past few weeks earning millions of views each, ‘samkandsydk’ are blowing people’s minds.

Sisters Sam and Syd K’s “blood harmony” goes viral on TikTok

At the moment, the duo’s most popular cover is of “Dream” by Fleetwood Mac. This is quite fitting, given the song’s history on TikTok.

Their rendition, which already has over 3 million views, has amazed listeners and didn’t need any hashtags in the caption to go viral. Instead, people seem simply fascinated by the harmonization – which is so synchronized that it sometimes sounds like just one person singing.

One user replied, “The fact that this wasn’t one voice at the beginning blows my mind.” Another was simply puzzled: “Can someone explain what’s happening, how is this real?”

To answer the question, this does seem to be real. In their other viral video, a cover of Keane’s “Somewhere Only We Know,” numerous commenters discussed the vocal phenomenon at hand.

One user explained why their talent is so mesmerizing: “In music we call this a ‘blood harmony’ and it’s the most beautiful from siblings… y’all have a gift.”

On an app full of popular funny videos using the “Duet” feature, Sam and Syd’s duets seem to have struck a different chord with users.