ScienceDaily (Dec. 11, 2009) Is it a boy or a girl? Expecting parents may be accustomed to this question, but contrary to what they may think, the answer doesn't depend solely on their child's sex chromosomes.
Scientists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany and the Medical Research Council's National Institute for Medical Research (NIMR) at Mill Hill, UK discovered that if a specific gene located on a non-sex chromosome is turned off, cells in the ovaries of adult female mice turn into cells typically found in testes. Their study, published in Cell, challenges the long-held assumption that the development of female traits is a default pathway. At the same time, it grants a valuable insight into how sex determination evolved.
& 
Compatiable 