Which of the following describes Dizygotic twins?

• A. Identical twins sharing 100% of genes
• B. Not identical and share 50% of genes
• C. Formed from one fertilized egg only
• D. Identical twins with no physical differences

Answer: (B)

Dizygotic twins, also known as fraternal twins, are the result of the fertilization of two separate eggs by two separate sperm cells. This means they share approximately 50% of their genetic material, similar to any other siblings born at different times. They are not genetically identical like monozygotic twins (identical twins), who stem from a single fertilized egg and share 100% of their genes.

The fact that dizygotic twins are formed from two distinct fertilized eggs is critical to understanding their genetic makeup and the variation that can occur between them. Unlike identical twins, fraternal twins can vary significantly in traits such as appearance, personality, and even some health characteristics due to the differences in their genetic contributions from their parents. These factors contribute to their classification as "not identical" twins.

The other options describe characteristics that do not apply to dizygotic twins. Identical twins sharing 100% of genes refers specifically to monozygotic twins. Forming from one fertilized egg only describes monozygotic twins as well, and the statement about identical twins with no physical differences is inaccurate since even identical twins can have distinguishing features due to environmental factors. Thus, the correct answer highlights the key