Everyone has different fingerprints on their fingers. Fingerprint is determined by genes, and once it is formed, it becomes a symbol of someone's life. Even if the epidermis is damaged by knife wound and scald, the fingerprint remains unchanged after wound healing. Fingerprint is composed of lines with different length, shape, thickness and structure, which can be divided into three basic types: bucket, dustpan and bow. Because everyone's fingerprints are different, all countries use fingerprints to replace the history of seals and signatures, and public security organs can also solve cases according to the fingerprints left by criminals when they commit crimes. In addition, we can see some signs of genetic laws and diseases from fingerprints. If there is congenital dementia, this patient's fingerprints are unusual. Therefore, scientists continue to explore the use of fingerprints, palm prints and soles to diagnose diseases. Why do twins look alike?

Twins that we usually see in life or on TV usually look alike. Do you know why? There are two kinds of twins. One is twins, that is, a woman releases two eggs at the same time, and each of them is fertilized with a sperm to become two fertilized eggs. Because they evolved from different eggs, and each egg contains different genetic structure, such twins often have different sexes, and their physical characteristics and appearance are not necessarily similar. The other is identical twins, that is, in the early stage of the whole embryo development, for some reason, the fertilized egg forms two blastomeres at the first division, and each develops into a fetus. This kind of twins have the same genetic characteristics, their gender is often the same, and their blood type, appearance, figure, intelligence and personality characteristics are also very similar.