For more than forty years we have followed a richly characterized cohort of identical and fraternal twins and their relatives, collecting behavioral measures and banked biological samples across the lifespan. That longitudinal resource gives us an unmatched window into how early-life experiences and midlife exposures interact with genetic risk to shape late-life brain health. Adding siblings, parents, grandparents, and other family members to this resource will dramatically improve our ability to separate inherited genetic effects from shared environmental influences. Family-based samples make our genetic analyses far more powerful and precise but recruiting participants and processing samples is expensive. Your gift directly removes this barrier and accelerates the discoveries that will inform prevention and treatment.