While plants and lower forms of animal life have been successfully cloned for many years now, before Wilmut's announcement it had been thought by many to be unlikely that such a procedure could be performed on higher animals. ... However, despite how many or how few individual characteristics twins have in common, they are different people. ... Some psychological characteristics may be biologically based and the parent will know in advance what crisis a cloned teenager will go through and how he or she will respond. ...