血缘 (xuè yuán) literally means 'blood origin' — 血 (xuè) means 'blood', and 缘 (yuán) means 'origin', 'source', or 'connection'. Together, they refer to biological kinship: the genetic relationship between people who share common ancestors, such as parents and children, siblings, or cousins. Unlike social or legal relationships (e.g., adoption), 血缘 emphasizes shared DNA and hereditary ties.

This term is commonly used in discussions about family history, genetics, inheritance, marriage restrictions (e.g., laws prohibiting marriage between close blood relatives), and even animal breeding (e.g., purebred livestock). It carries a formal, neutral tone and appears frequently in academic, legal, and medical contexts — though it’s also used in everyday conversation when distinguishing biological from non-biological family ties.