After the funeral, we will have a gathering of blood relatives.
Koichi's blood relatives are all tall.
My dad isn’t a blood relative but I still think of him as my real dad.
Your tribe's blood (lots of inbreeding) are the blood of your relatives. These are blood relatives.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.