This is not normal. Although they are sisters, they are not twins. Sika was born several years before crystal. Although her parents have not changed, in this case, the two sisters are not very similar. . If you ask your parents to give you another brother or sister, you two are definitely not alike. . . Because the gene combination is uncertain, it may be Sika's A and B gene combination, and Crystal's A and B gene combination. . So because they are not the same child, they will not be very similar. . . Ll: If you don't believe me, you can ask your biology teacher. . That's what my biology teacher said anyway. The selective expression of different genetic materials and genes leads to different traits.