Children of people infected with hepatitis B virus may have acquired the hepatitis B virus susceptibility gene from their parents. They may share with their parents some inherited immunodeficiency in protection against hepatitis B virus infection. Therefore, close contact in the family after birth is the main route of paternal-infant transmission of hepatitis B. However, fathers are far less likely than mothers to transmit hepatitis B virus to their children, about 26% prior to vaccine use. Since hepatitis B is completely preventable by vaccination of newborns, paternal-infant transmission is no longer a major problem in hepatitis B transmission. However, newborns should always be tested for antibodies to the hepatitis B virus after completing the full course (3 doses) of hepatitis B vaccination. This is because a small number of infants do not produce sufficient antibodies to the hepatitis B virus after 3 doses of vaccine, and such children may still be infected with the hepatitis B virus. In addition, children should be tested again for hepatitis B virus antibodies when they reach the age of 3 to 6. If the antibody titer drops below 10 IU/ml, they should be given a booster immunization with the hepatitis B vaccine to stimulate the body to develop immunity to the hepatitis B virus again. As long as the child has received the hepatitis B vaccine on time and has developed surface antibodies to the hepatitis B virus, the hepatitis B father can have normal contact with his child, make out with him, and do his fatherly duty.