“How do I know if the child is mine …… can not go to do paternity testing ……” The man’s words have not fallen, a woman holding the swaddled baby, has long been sobbing. What happened in the end? The above scene happened in my clinic, although a full year has passed, but still vivid. A year ago today, a couple came into my clinic, and they looked like they were 95 years old. They brought the baby to me and asked me to “save” the 3-month-old baby boy in the swaddling clothes. I immediately saw the “special feature” of the baby’s left hand, his left ring finger and little finger had grown together, as if they were stuck together with glue. “I analyzed the baby’s condition to the couple and told them to wait until the baby was about 6 months old (weighing ≥6kg or more) to have the deformity corrected by means of a joint finger splitting operation. Compared to the wife’s anxiety and panic, the husband seemed unusually calm and asked after a long time, “Doctor, what is this caused by?” At present, the etiology of juxtaposed finger deformity is not clear. Previous studies have shown that it is mainly related to genetic factors, embryonic developmental factors, and external factors. The genetic factor, that is, if one of the parents has a “precedent” in the family, may inherit this malformation; embryonic developmental factor, that is, during the development of the embryo, certain genetic mutations lead to syndactyly; external factors, that is, the mother is affected by external adverse environmental influences during pregnancy, such as drugs, diseases, radiation, etc., leading to syndactyly. I told the couple in detail about the cause of the disease, but the husband seemed “puzzled” by the genetic factor. “We (the couple’s family) have not had this ‘disease’ for three generations, so how can it be hereditary?” “It is difficult not to child is ……” I do not know if it is because the husband and wife relationship is not good, the husband’s face gradually heavy, frowning. Just when I was going to talk to them again about the surgery, the husband took the lead and snapped, “How do I know if the child is mine …… can’t go for a paternity test ……” The wife listened The wife cried on the spot. The final is a “false alarm” “clear officials can not break family affairs”, the scene was slightly awkward, I desperately want to ease the atmosphere that seems to be cold to the freezing point. I further explained to them, “and refers to the cause of the disease is unknown, not necessarily genetically caused, there may be other factors ……” While talking, the accompanying mother-in-law turned out an old photo in the phone album. It was a rare photo of the baby’s great grandfather (dad’s grandfather). Although the photo is close to destruction, but the mother-in-law can be sure that the baby’s great grandfather is actually also a and finger deformity “patients”. It’s just that the grandfather left early, and even the baby’s father never met him, and few people mentioned the matter of parallel fingers. It was a “false alarm”! In fact, parallel finger inheritance is not limited to two or three generations, and this baby’s story is a good example. The majority of cases of juxtaposition are inherited in an autosomal dominant manner, and some are inherited in an autosomal recessive manner. Studies have shown that if a dominantly inherited patient marries a normal person, there is a 50% chance that the offspring will have a parallel finger; if a recessive patient marries a carrier of the same disease-causing gene, there is a 50% chance that the offspring will have a parallel finger; and if a recessive patient marries a normal person, although the offspring are all carriers of the gene, they generally do not have a parallel finger deformity. In other words, syndactyly can be inherited, but not always due to genetic factors. This is one of the main concerns of many parents. The parents have been very cooperative since the initial consultation, and they brought their baby in for the syndactyly surgery when he was just over 6 months old. The baby’s surgery went well and was successful, and the parents are very satisfied with the good postoperative recovery, the hidden scar, no skin pigmentation, and no abnormal finger sensation or function.