Sixth finger is a six-finger deformity that occurs due to genetics, environment during pregnancy, and other factors. 1. Heredity: Six-finger deformity is considered to be directly related to heredity. For example, if someone in the previous generation had a six-finger deformity and was affected by hereditary factors, the chances of their offspring having a six-finger deformity, may increase significantly. 2. Pregnancy environment: Six-finger malformation can be considered to be related to the influence of environmental factors. During pregnancy, especially in the early stages of pregnancy, a woman’s exposure to viral infections, certain medications, frequent exposure to radiation and other harmful substances may increase the chances of the fetus having a six-finger deformity. 3. Other factors: underage pregnancy, gestational diabetes mellitus, smoking during pregnancy, exposure to chemicals during pregnancy and occupational exposure to hazardous substances may increase the risk of fetal six-finger malformation. To summarize, there are various reasons for the occurrence of six-finger malformation, it is recommended that during pregnancy, women should strengthen the health care and nutrition during pregnancy, avoid exposure to radiation, drugs and other factors that can lead to embryonic malformation, and undergo regular obstetric examination in regular hospitals.