Consanguineous marriage is the common ancestor of both men and women within three generations, that is, blood relatives beyond three generations are not considered close relatives. For example, if you count as the first generation, your father or mother is the second generation, and your grandfather or maternal grandfather is the third generation, then you and the great-grandfather or maternal great-grandfather of the marriage object are in common, and marriage is allowed.
First, every few generations is not consanguineous marriage
Consanguineous marriage means that the common ancestor of both men and women is within three generations, that is, there is direct or collateral blood relationship within three generations. Marriage of close relatives is one of the conditions that marriage is forbidden by the marriage law of our country.
Non-consanguineous marriage requires more than three generations of blood, such as you count as one generation, your father or mother is the second generation, and your grandfather or maternal grandfather is the third generation. If you and your spouse's great-grandfather or great-grandfather are in common, marriage is allowed.
Second, the harm of consanguineous marriage
(1) Marriage between close relatives increases the chance of recessive genetic diseases in the next generation, such as albinism and congenital deaf-mute; Cerebellar malformation, phenylketonuria, galactosemia, etc. It can also increase the incidence of polygenic genetic diseases, common diseases are hydrocephalus, spina bifida, anencephaly, schizophrenia, congenital heart and epilepsy.
2, closely married couples carry the same recessive pathogenic genes are very likely to meet in the offspring, and the incidence of genetic diseases in the offspring is increased.