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Better Health Channel: Identical and Fraternal Twins
The Better Health Channel of Victoria, Australia, offers information on twins. Factors that increase the odds of having twins, how different types of twins originate, possible birthing complications, and zygosity testing are covered.
BiologyWise
Biology Wise: Homozygous vs. Heterozygous
Genetic traits are described as homozygous or heterozygous based on allele similarity. Homozygosity and heterozygosity are explained in this resource. Includes a chart highlighting their differences and some examples that occur in humans.