Anxiety can be chemical or environmental. It is a mental illness in many cases and needs a doctor’s treatment. However, not everyone who is anxious has clinical level anxiety. In studies on attachment, it is a good idea to look at research that is based on Erik Erikson social-emotional development theory. And most of the research I have read over the years (I am in early childhood) is that the level of attachment a child has with a caregiver (does not require to be a parent) highly effects his/her ability to attach in adulthood.