Speaking only from the perspective of being in Hawai'i, here the question of blood quantum is complicated and much different than many ndn tribes. To be entitled to Hawaiian homestead land under an act of Congress passed in 1920, a person must be 50% blood quantum. However, to be eligible for any other Hawaiian benefit (attend a private school, obtain scholarships, grant funding, loans, etc.) one need only show one drop of blood. There are many people here who identity as Hawaiian and who are considered cherished elders or kupuna in the community who have very little Hawaiian blood. But as to your other point, if the person was not raised in the community with the traditions then no matter how much blood they have they may not be considered "Hawaiian."