Evaluation methods for evaluating susceptibility to multifactorial diseases in sexual differentiation disorders, human estrogen receptor alpha (.alpha.) genes carrying single nucleotide polymorphisms (SNPs) associated with the multifactorial diseases, DNAs containing the nucleotides at the SNPs, and diagnostic markers containing the DNAs are provided. Susceptibility to the multifactorial diseases can be evaluated by examining at least one of SNPs 8 to 14, or SNPs 10 to 14, in a human estrogen receptor .alpha. gene, and more precisely evaluated by examining a diplotype encompassing SNPs 10 to 14.