Physiological characteristics of twins Twins develop from the same group of fertilized eggs, so their genetic makeup is basically the same. Physically, twins share many characteristics. For example, twins are very similar in height, body shape, face and other physical characteristics. In addition, some special phenomena often occur in twins. For example, some twins will be born with the same fingerprints, and their stem cells and tissue blood types will be relatively similar. However, because different embryos divide in different ways