What does blood relationship mean in genetic terms?

Blood relationship refers to the degree to which genes are shared. Close relatives, such as parents, children and siblings, share many genes in common. For example, parents and children share 50% of their genes, and siblings also share about 50%.This genetic link is formed by genes inherited from a common ancestor. The closer the blood relationship, the more genes there are in common and the more similar the genetic characteristics and risks are.

How much genetic difference does it take to be unrelated?

To be considered unrelated, the number of genes shared must be very small or statistically negligible. Typically, parents, children and siblings share about 50% of their genes, while cousins share about 12.5%.Usually, a person is considered to be unrelated if they share less than 1% of genes or none at all.

However, genetic testing assesses the presence or absence of consanguinity on the basis of individual gene variants and concordance rates. Statistical analysis and comparison of specific genetic markers play an important role.