The term 'Grapefruit Relative' refers to two citrus fruits, the UGLI and the POMELO. The UGLI is a hybrid of grapefruit, tangerine, and orange, and is native to Jamaica. It has a thick, bumpy skin and a tart flavor. The POMELO is a large citrus fruit that is native to Southeast Asia. It has a sweet flavor and a thick, yellow-green rind. Both the UGLI and the POMELO are related to the grapefruit and share many of its characteristics.