Human chimera could have Evolutionary Advantage?
In 1953 a human chimera was reported in the British Medical Journal. A woman was found to have blood containing two different blood types. Apparently this resulted from cells from her twin brother living in her body. . More recently, a study found that such blood group chimerism is not rare. Another report of a human chimera was published in 1998, where a male human had some partially-developed female organs due to chimerism. He was conceived by in-vitro fertilization.