Just because it's translated "blood relative" only means the translator thought that made sense. I'm drawing from the discussion of this point in Colin Hamer's "Marital Imagery in the Bible" (2019), where he notes in Hebrew and Arabic "the word 'flesh' is synonymous with clan or kindred group" as in "Leviticus 25:49 where ESV translates בְּשָׂר֛ (flesh) as 'clan'."

https://www.google.com/books/edition/Marital_Imagery_in_the_Bible/f7qCDwAAQBAJ?hl=en&gbpv=1&dq=%22Leviticus+25:49%22+flesh+clan&pg=PA37&printsec=frontcover