Complex diseases such as cardiovascular disease, pterygia, glaucoma, and myopia are caused by polygenic, environmental and lifestyle factors. Studying genetics of complex diseases within population isolates has multiple benefits over studies conducted in single families and unrelated populations. Generally, there is increased power to detect heritable effects. Also, the presence of multiple households within an extended pedigree disentangles confounding environmental variables from true genetic effects. Isolated populations also contain greater potential for identifying underlying causal quantitative trait loci. This thesis work focuses on heritability and genome-wide linkage analyses of cardiovascular disease and three eye diseases: pterygia, glaucoma, and myopia in the Norfolk Island population isolate. This study investigates gene-environment interactions of four complex diseases: cardiovascular disease, pterygia, glaucoma, and myopia.