First off, I only got one genetics question on my DAT, so I can't speak from first hand. I also took a genetics class and felt very comfortable with the subject, but I had read about a lot of genetics questions like you did and heard that Campbell's biology book seventh edition was very good. I borrowed my friend's and read their sections on genetics and found it to be extremely useful. It not only reviewed the stuff from my genetics class well but it went over some technical stuff that I didn't know. You can get this book on amazon for pretty cheap too. Hope this helps