noun
Formal or legal term for a person related by blood, as opposed to in-laws or adopted family.
彼は私の血縁者ではありません。
He is not my blood relative.
遺産は血縁者に相続される。
The inheritance is passed on to blood relatives.
肉親 refers to close blood relatives like parents, children, and siblings, with a more emotional nuance, whereas 血縁者 is a neutral, legal term.
血縁 (blood relation) + 者 (person). A straightforward kanji compound.