The extreme male brain theory is one of the 'everyone is on a spectrum, and those at one end of it are diagnosed as autistic' theories (i.e. continuum within the population) whereas genetic theories are predicated on there NOT being a continuum in the general population (or at least, if there is, we don't have any good evidence for it as the population studies that have been done so far have been flawed). I actually went to a lecture not long ago where the lecturer essentially compared these two approaches to thinking about autism and concluded that the genetic approach has more merit than the continuum approach.