Answer: They are sterile
Explanation:
Mule is a hybrid of male donkey and female horse with different chromosome number and is considered superior to both horse and donkey. Still it is considered as a weak hybrid this is because the mule is sterile which means that it cannot reproduce further.
The mule though is superior in many ways such as it can jump and is strong. The hybrid of mule is not good as it cannot continue its next generations on earth.
They are sterile and so is a weak hybrid.
Chromosomes are Inherited From Your Parents. One chromosome from each of your 23 pairs came from each of your parents. The two chromosomes of a pair (except for the sex chromosomes) contain the same genes, but the genes have small differences. Things like SNPs make each copy of a gene uniquely Mom's or Dad's.
The side of a mountain range that faces the wind often receives more moisture then the downwind of the same range