Genetics is one of the causes of hand and foot deformities in babies, and if one of the parents, or grandparents, has a hand and foot deformity, the baby may also have a hand and foot deformity. I was very impressed with a family where the grandfather had syndactyly, and so did the father, and so did the baby, and the syndactyly was exactly the same type of syndactyly, which is a very obvious genetic predisposition. If no one in the family has hand and foot deformities and the baby is the first case, what is the reason for this? In summary, there are several reasons as follows: i. The mother was sick and unwell in the early stages of pregnancy; ii. The mother used medication during pregnancy; iii. The mother’s overall health was not good during pregnancy and her nutritional intake was inadequate; iv. She was exposed to some abnormal physical or chemical factors. Although it is not true that 100% of babies will develop hand and foot deformities after having a certain cause, the percentage of babies with hand and foot deformities increases after having a cause, so parents should pay more attention to it.