Clones "may be up to four times bigger than normal animals and the placenta might be up to seven times bigger than in normal animals, " Jaenisch said.

CNN: Cloning experts to tell House committee pros, cons

Rudolf Jaenisch. (Applause.) The 2010 National Medal of Science to Rudolph Jaenisch, Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, for improving our understanding of epigenetic regulation of gene expression, the biological mechanisms that affect how genetic information is variably expressed.

WHITEHOUSE: President Obama Honors the Country??s Top Innovators and Scientists | The White House