The degrees of consanguinity

Degrees of consanguinity are a measure used to determine the kinship between two people. They are based on the number of generations separating individuals and the number of common ancestors they have in their family tree.

It is important to note that degrees of consanguinity can be relevant in certain legal fields, such as family law or inheritance. For example, in some countries, marriage between people who have a close degree of consanguinity, such as between siblings or between first cousins, is prohibited because of the increased risk of genetic problems in the offspring. Also, the degree of consanguinity may be a factor to consider in the distribution of assets in an inheritance, as heirs with a closer degree of consanguinity often have preferential rights to the deceased's assets.

What is kinship?

Kinship is the relationship that exists between two or more persons who are descended from the same ancestor or who are united by family ties, whether by consanguinity, affinity or adoption.

There are different types of kinship, which are classified according to the type of link between the persons:

• Kinship by consanguinity: This is between people who are descended from the same biological ancestor, either in the straight line (such as between parents and children) or in the collateral line (such as between siblings, aunts, uncles and nephews, cousins, etc.). Kinship by consanguinity is determined by degrees of consanguinity, which measure the number of generations separating individuals and the number of common ancestors they have in their family tree.
• Kinship by affinity: This is between people who are not linked by biological ties, but by marriage or common-law marriage. For example, a person's spouse is related by affinity to his or her partner's relatives. Kinship by affinity extends to the immediate family members of each spouse, such as parents, siblings and children.
• Kinship by adoption: This is between people who do not have a biological link, but who have been united by a legal process of adoption. For example, an adoptive parent is related to an adopted child and vice versa. Kinship by adoption has the same legal effects as kinship by blood, such as the right to inherit, the right to maintenance, etc.

What are the degrees of consanguinity?

1. First degree: The first degree of consanguinity is between parents and children, i.e. between people who have a common ancestor in the previous generation. The degree of consanguinity is 1, as there is only one generation separating them.
2. Second degree: The second degree of consanguinity is between siblings, i.e. between persons who have two common ancestors in the previous generation. The degree of consanguinity is 2, as there are two generations separating them.
3. Third degree: The third degree of consanguinity is between uncles and nephews, i.e. between people who have three common ancestors in the previous generation. The degree of consanguinity is 3, as there are three generations separating them.
4. Fourth degree: The fourth degree of consanguinity is between first cousins, i.e. between people who have four common ancestors in the previous generation. The degree of consanguinity is 4, as there are four generations separating them.
5. Fifth degree: The fifth degree of consanguinity is between second cousins, i.e. between people who have five common ancestors in the previous generation. The degree of consanguinity is 5, as there are five generations separating them.
6. Sixth degree: The sixth degree of consanguinity is between third cousins, i.e. between people who have six common ancestors in the previous generation. The degree of consanguinity is 6, as there are six generations separating them.

Difference between degrees of consanguinity and degrees of affinity

The degrees of consanguinity and affinity are two ways of measuring kinship between people, but they differ in the way the link is established.

The degree of consanguinity measures the relationship between people who are related by blood, i.e. by having a common ancestor. The number of generations separating the individuals is counted and a degree is assigned to each generation. For example, between parents and children there is one degree of consanguinity, between siblings there are two degrees, between uncles and nephews three degrees, and so on. The degree of consanguinity can be important in matters such as inheritance, filiation, guardianship and other legal matters.

On the other hand, kinship by affinity is established through marriage or common-law marriage. This type of kinship is not based on blood, but on the relationship between two people who are united by marriage or partnership. Kinship by affinity extends to the immediate family members of each spouse, such as parents, siblings and children. For example, a person is related by affinity to his or her spouse's parents, to his or her spouse's siblings and to his or her spouse's children. Kinship by affinity can be relevant in matters such as maintenance law, inheritance, adoption, among others.