However, this may not be the case. Harris argues that children's peers have more influence on one's personality than their parents. The common example used is a child with immigrant parents. The children are able to continue to speak their parent's original language whilst at home, but the children can also learn the new language and speak it without an accent, while the parents' accent remains. Harris claims that children learn these things from their peers in an attempt to fit in with others. In the nature versus nurture debate within secure attachment, Harris takes a nature stance. She supports herself by stating that identical twins separated at birth showed more similarities in their hobbies and interests than twins raised in the same household. Aside from the nature argument, there are three additional criticisms. The attachment is assessed during momentary separations. Since these brief situations can be stressful, this is a limitation in the theory. A better demonstration of the child's reaction might have come from a situation in which the mother left, but the child did not experience excessive stress. Another limitation with the attachment model is the assumption that the mother is the primary attachment figure. Attachment can be expressed differently with each figure. For example, children may cry when one figure leaves while they might have trouble sleeping when another leaves. Additionally, physiological changes can occur during this situation, and they were not accounted for.