Let me simplify it. Your uncle's wife's nephews or nieces, or your auntie's husband's nephews or nieces, are your cousins, that are not related to you by blood.

The question is can you marry them since you guys are not related by blood.

It will be described as consanguinity. Though, practiced by many parts of the world. The northern part of Nigeria.In Egypt, around 40% of the population marry a cousin. A 1992 survey in Jordan found that 32% were married to a first cousin; a further 17.3% were married to more distant relatives.67% of marriages in Saudi Arabia are between close relatives as are 54% of all marriages in Kuwait, whereas 18% of all Lebanese were between blood relatives. The incidence of consanguinity was 54.3% among Kuwaiti natives and higher among Bedouins.It has been estimated that 55% of marriages between Pakistani Muslim immigrants in the United Kingdom are between first cousins, where preferential patrilateral parallel cousin marriage, i.e. a man marrying the daughter of his father's brother, is favored.
However, this practice seems widespread and enjoyed by many but the downside of this practice is that it tends to increase the incidences and burdens of genetically related diseases.

single-gene inherited disorders include;
cystic fibrosis,
alpha- and beta-thalassemias,
sickle cell anemia (sickle cell disease),
Marfan syndrome,
fragile X syndrome,
Huntington's disease, and
hemochromatosis.

Examples of multifactorial inheritance include;
heart disease,
high blood pressure,
Alzheimer's disease,
arthritis,
diabetes,
cancer, and
obesity.

Chromosomal abnormalities include; Down syndrome, Turner syndrome.

So, if you want to consider consanguinity because of the love you have for your cousins, please consider the above listed conditions. The list is by no means exhausitible.
Good luck.

johnubimago:
It will be described as consanguinity. Though, practiced by many parts of the world. The northern part of Nigeria.In Egypt, around 40% of the population marry a cousin. A 1992 survey in Jordan found that 32% were married to a first cousin; a further 17.3% were married to more distant relatives.67% of marriages in Saudi Arabia are between close relatives as are 54% of all marriages in Kuwait, whereas 18% of all Lebanese were between blood relatives. The incidence of consanguinity was 54.3% among Kuwaiti natives and higher among Bedouins.It has been estimated that 55% of marriages between Pakistani Muslim immigrants in the United Kingdom are between first cousins, where preferential patrilateral parallel cousin marriage, i.e. a man marrying the daughter of his father's brother, is favored.
However, this practice seems widespread and enjoyed by many but the downside of this practice is that it tends to increase the incidences and burdens of genetically related diseases.

single-gene inherited disorders include;
cystic fibrosis,
alpha- and beta-thalassemias,
sickle cell anemia (sickle cell disease),
Marfan syndrome,
fragile X syndrome,
Huntington's disease, and
hemochromatosis.

Examples of multifactorial inheritance include;
heart disease,
high blood pressure,
Alzheimer's disease,
arthritis,
diabetes,
cancer, and
obesity.

Chromosomal abnormalities include; Down syndrome, Turner syndrome.

So, if you want to consider consanguinity because of the love you have for your cousins, please consider the above listed conditions. The list is by no means exhausitible.
Good luck.

What if they are not blood relatives and they are just cousins-in-law?

By definition, a cousin is a relative that is the child of a parent's sibling, this is more specifically referred to as a first cousin.
A cousin is a type of relationship in which relatives are two or more generations away from their most recent common ancestor. For this definition Degrees and removals are used to further specify the relationship.
Regardless, of the degree, the inherited traits will definitely find its way in the lineage because cousins are related by blood.

johnubimago:
By definition, a cousin is a relative that is the child of a parent's sibling, this is more specifically referred to as a first cousin.
A cousin is a type of relationship in which relatives are two or more generations away from their most recent common ancestor. For this definition Degrees and removals are used to further specify the relationship.
Regardless, of the degree, the inherited traits will definitely find its way in the lineage because cousins are related by blood.

What about the cousin of your cousin that is not related to you by blood?

While your uncle's children are your cousins, the nephew or niece of your uncle's wife are cousins to your uncle's children but not blood relatives to you.

Even me here can't understand all you re saying or asking or anything at all, you just confusing the whole cousin setup. Are you looking for validation for fvcking or dating your cousin? Go ahead please that's no one's business. Matters plenty

lordnkem000:
Even me here can't understand all you re saying or asking or anything at all, you just confusing the whole cousin setup. Are you looking for validation for fvcking or dating your cousin? Go ahead please that's no one's business. Matters plenty

E be like say dis one don chop breakfast, simple post baba no fit comprehend. Baba carry your aggression somewhere else jare.

johnubimago:
By definition, a cousin is a relative that is the child of a parent's sibling, this is more specifically referred to as a first cousin.
A cousin is a type of relationship in which relatives are two or more generations away from their most recent common ancestor. For this definition Degrees and removals are used to further specify the relationship.
Regardless, of the degree, the inherited traits will definitely find its way in the lineage because cousins are related by blood.

Chatgp photocopier I de greet o.

Merry100:

E be like say dis one don chop breakfast, simple post baba no fit comprehend. Baba carry your aggression somewhere else jare.

No na am not aggressive, me and u na one na, I just no understand your questions o. Sorry if I sound aggressive my friend