The family has "adopted" Jeremy as "fictive kin".
Kinship is a feeling of being identified with someone else or people. I'm almost certain that a many people have gone to the agreement that family is essential, be that as it may, we can't generally depend on our families. In some cases we don't live with them. Perhaps they're in another state, or significantly another nation. Maybe our association with our family is confused and we're not as affectionate as some different families. Whatever the case, our "family," the ones that we consider to be such a result of blood and law, can't be there for all of us the time. That is the point at which the possibility of fictive kin becomes an integral factor.