The generation reason of the person that join system is gene mutation of course, this kind of situation is more unusual, what because the mankind is in,a few ten million had formed evolution to be stabilized quite after year is alkaline base to mechanism of transcribe, expression, if this process gets the interpose of exterior element, have with respect to likelihood occurrence problem, the embryo that causes deformation appears.
The person that join system is an oosperm commonly mutation appears in disrupt process, local development is too mature, form all sorts of common the situation of the body. For instance common a cerebra, or two cerebra are common a body, appear occasionally two almost complete bodies, but the part is splanchnic join system, pass an operation to be able to be solved so, but risk dispute Chang Zhi is big.
The odds that the person that join system can survive is very small, the mankind also has ego to protect a mechanism, in embryo of the person that join system period had died, the person joining system that can survive maintains a few years very hard also commonly. Avoiding the method that appears even body person is between gestation utmost reduces exterior element to disturb, for instance radiation, once discover, as soon as possible intervenes, concern likely still with oneself constitution.
