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Biology Project: The Gene Machine
Site allows users to learn interesting information about their genes based on his/her physical traits. Provides a brief explanation of how a person's genotype is determined.
University of Utah
University of Utah: Learn Genetics: Genes and Blood Type
For a concise summary of human blood types, this is a great resource. Discussion includes the topics of genotype, phenotype and agglutinins. There is also a nice pictorial table that summarizes the three blood types.