The present invention generally provides a rapid efficient method for analyzing polymorphic or biallelic markers, and arrays for carrying out these analyses. In general, the methods of the present invention employ arrays of oligonucleotide probes that are complementary to target nucleic acids which correspond to the marker sequences of an individual. The probes are typically arranged in detection blocks, each block being capable of discriminating the three genotypes for a given marker, e.g., the heterozygote or either of the two homozygotes. The method allows for rapid, automatable analysis of genetic linkage to even complex polygenic traits.