Biermann faced towards the beach for the racy snap, showing off the sparkly thong.
Her mom, 43, responded to the photo with eye-roll and laughing emojis, writing, “so mad you posted it first,” before adding, “I bought it for us both crazy.”
Followers, including Brielle’s 19-year-old sister Ariana Biermann, dropped heart-eye and fire emojis in the comments, while one fan wrote, “the genetics in this family are unreal.”
Others were less focused on their shared genes and more focused on their shared thong, with one commenter wondering, “Are we just gonna ignore the fact that they share thongs.”
“You share G Strings?” another asked, racking up 163 likes, while a third added, “Never knew ppl shared thongs….”
The mother-daughter duo’s black G-string is similar to the vintage Gucci thong Kim Kardashian famously modeled back in 2018 — although the brand doesn’t appear to have ever sold embellished versions, meaning the Biermanns’ could be a knockoff.
It’s unclear whether Kardashian ever shared the style with members of her famous family.
Zolciak and her daughters often rock similar swimwear, and she and Ariana hit the beach in matching leopard-print bikinis from the “Real Housewives of Atlanta” alum’s Salty K swim line in July.
Brielle frequently shows support for her mom’s swimwear line as well, posting photos of herself rocking thong bikinis from the label.
During a 2018 game of “Love It or Weave it,” Brielle and Kim even told Page Six Style that they both “love” belfies, or butt selfies.
Perhaps the family that belfies together, stays together.