Like peas in a pod. That's how people often describe the relationship between twins who share everything from a birthday to clothes, friends, and toys. But where does another sibling fit into the mix? The extra brother or sister to a set of twins may feel left out when it comes to the bond that his or her siblings created in the womb. Does a brother or sister of twins have as close of a relationship with twin siblings as he or she would if the twosome had been single births?