Crosses
 
 
  (A)     agouti     X     agouti     →     all agouti  
 
  (B)     yellow     X     yellow     →     2/3 yellow: 1/3 agouti  
 
  (C)     agouti     X     yellow     →     1/2 yellow: 1/2 agouti  
 

Inheritance patterns in three crosses involving the normal agouti (gray-brown color) allele and the mutant yellow allele in the mouse do not follow any of the Mendelian dominance patterns.