The research into the relationship of early attachment and adult relationships arecorrelational rather than experimental, therefore acause and effect cannot be establishedbetween the attachment type and later adult relationships. Analternative explanationof therelationship between early attachment and later adult relationships is Kagan’s temperament hypothesis, which is the idea that an infant’s temperament (innate emotional personality) explains their attachment behaviour, as infants with an easy temperament or easier to interact with and form a secure attachment, whereas the infants with a difficult temperament tend to be insecurely attached. Therefore,it may be the individual’s temperament that explains the nature of their adult relationships.