SQL luid

Jcreason set you right. If you need to connect tables to list lookups the lookup_id in the core_lookup table connects to another table's luid. You asked about the core_family_member.role_luid so as an example:

SELECT
P.person_id,
P.first_name,
P.last_name,
FMR.lookup_value AS family_role
FROM core_person P
LEFT OUTER JOIN core_family_member FM ON FM.person_id = P.person_id
LEFT OUTER JOIN core_lookup FMR ON FMR.lookup_id = FM.role_luid AND FMR.organization_id = 1
WHERE FM.role_luid = 29

29 would select adults.