B. Somatic cells in organisms are formed by the division and differentiation of fertilized eggs. One pair of genes in a fertilized egg comes from the father and the other pair comes from the mother. If b comes from father, then b must come from mother, and b is correct;

C. Although the trait controlled by recessive gene B cannot be expressed in offspring, the recessive gene will be passed down from generation to generation, so the trait controlled by B belongs to genetic trait, and C is wrong;

D, when a pair of genes controlling a trait in a cell, one is dominant and the other is recessive, then only the trait controlled by the dominant gene will be displayed. Therefore, Bb individuals show the character controlled by B, and D is correct.

So choose: C.