Both men and women have reached the legal age of marriage, and there is no compulsion from others or interference from a third person. The application for marriage by both men and women is completely voluntary and meets the conditions and requirements for applying for marriage as stipulated in the Marriage Law. However, in any of the following circumstances, marriage registration is still not allowed:
 （1） Direct blood relatives and three generation collateral blood relatives;
 （2） Suffering from diseases that are medically considered not to be married. This is because the marriage of lineal relatives and three generations of collateral relatives belongs to consanguineous marriage. As a result, the offspring are likely to have the same pathological genes, which increases the incidence of some recessive genetic diseases, such as congenital flaccidity, congenital ichthyosis, congenital hypertension, schizophrenia, congenital heart disease, anencephalia Spinal bifida, epilepsy, etc. In order to improve the quality of the whole people and reduce the incidence of genetic diseases, it is very necessary to prohibit close marriage between cousins. "Suffering from diseases that are medically considered not to be married" mainly means that serious genetic diseases are congenital due to genetic factors, patients lose all or part of their ability to take care of themselves, and offspring are at high risk of reappearance; Direct blood relatives and three generation collateral blood relatives; Both parties are severely mentally retarded, and both are "suffering from diseases that are medically considered not to be married"
 2、 Whether the marriage registration can be entrusted to act as an agent for the marriage registration can not be entrusted by others. The parties to the marriage applying for marriage must go to the marriage registration authority of the civil affairs department above the county level to register in person. No other person can act as an agent to exercise this kind of civil rights. It is a civil activity. An agent accepts the entrustment of the principal and carries out civil activities in the name of the principal, Within the scope of authorization, the legal system in which the principal is responsible for the resulting civil liability is only applicable to the following four activities that are not personal:
 （1） The declaration of will has a strict personal nature, which must be expressed in person, such as will marriage registration;
 （2） Debt of strict personal nature, such as performance contract of specific actors;
 （3） The parties agree not to act as an agent;
 （4） The illegal act of marriage registration is a civil act with a very strict personal nature, which involves a series of personal and property relations such as rights and obligations between husband and wife. This declaration of intention must be made by the party concerned in person, and no other person may exercise it on behalf of the other party. If one of the parties applying for marriage is indeed unable to be present in person for some reason, At the time and place designated by both parties, they can request the marriage registration authority to register in person, and can also avoid the occurrence of arranged, forced, bought and sold, interference in the freedom of marriage and other illegal marriages. As stipulated in the Marriage Law, there are mainly two kinds of situations that marriage registration is not allowed, that is, close relatives get married and have diseases that are medically considered not to be married, But in practice, bigamy is also not allowed to be registered
 1、 This is easy to overlook. Going through the marriage formalities is related to our own interests. We need to express our willingness to go through the marriage registration in person, which can't be replaced by anyone. Therefore, the marriage registration can't be entrusted by an agent