By introducing functions of the phenotypes of a sib-pair as weight functions in the study of IBD processes, we present a unified non-parametric approach to linkage analysis of qualitative and quantitative traits in sib-pairs based on IBD data obtained from a set of polymorphic markers. With the introduction of weight functions and an appropriate conditional expectation of IBD processes, these statistical methods should be more efficient in the detection of genetic factors for complex diseases. These methods will be also useful in planning genetic studies. Large sample properties of these methods axe demonstrated.
