Why is mating between blood relatives discouraged from a genetic perspective?

The mating between blood relatives discouraged from a genetic perspective to avoid the expression of certain recessive genetic diseases.

Explanation:

Mendelian genetics proved us that there are 2 different traits namely the dominant trait and the recessive trait. The dominant trait gets expressed even if it is single whereas the recessive trait gets expressed only when both the haploid alleles are recessive in nature.

Most of the deadly genetic diseases are recessive in nature and hence if it is from the same family the 2 recessive alleles have a possibility to join together thereby causing the disease.

Inbreeding is simply defined as the mating of relatives. It is a mating system in which individuals carry alleles that originated from a common ancestor. Inbreeding is considered a problem in humans because inbreeding increases the chances of receiving a deleterious recessive allele inherited from a common ancestor.