Answer:
its being called a miracle because mules aren't supposed to give birth haha, they're sterile, they can't make sperm or eggs because their chromosomes don't match up well, and coz of chromosomes number.
Explanation:
 for example they have 31 and horses have 32 pairs of chromosomes so they cant match with anythin
 
        
             
        
        
        
Ik this in spanish but i dont know how can i translate this
        
             
        
        
        
10-35%25% based on the table the decrease of the table is 25%25%.Good Luck.