Definition of "zygosity" []

• The genetic condition of a zygote, especially with respect to its being a homozygote or a heterozygote. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Errors in zygosity determination systematically inflate heritability estimates for nonmendelian characters, because very similar DZ twins are wrongly counted as MZ, while very different MZ twins are wrongly scored as DZ."
• "(CVS) or fetal blood sampling are known as zygosity studies."
• "Respondents also completed a “zygosity” questionnaire (Nichols & Bilbro, 1966) which had an accuracy of 93% when matched with blood-typing (Kasriel & Eaves, 1976)."