Fraternal twin is a term used to describe a type of twin that is formed when two separate eggs are fertilized by two different sperm cells resulting in two genetically distinct individuals. The word "fraternal" is spelled as [frəˈtəːnəl] in IPA phonetic transcription. The first syllable is pronounced with a short "u" sound, followed by a double "t" and ending with a long "a" sound. The second syllable is pronounced with a long "o" sound and ending with a short "i" sound.
A fraternal twin refers to one of two siblings who are born from the same pregnancy but are not identical or monozygotic twins. These twins are the result of two separate fertilized eggs, also known as dizygotic twins, each implanted in the uterus and developing independently. Fraternal twins can be of the same sex or opposite sex and do not share more genetic material than any other siblings from different pregnancies.
The term "fraternal" emphasizes the non-identical nature of these twins, contrasting with "identical" or monozygotic twins. Due to the separate eggs being fertilized by different sperm, fraternal twins are genetically different from each other, just as any siblings from separate pregnancies would be. They may have similar physical features, but their genetic makeup is unique.
Fraternal twins are no more likely to be born to older women, nor are they influenced by hereditary factors more than regular births. They occur naturally in 1 out of every 80 pregnancies, with the likelihood varying among populations and demographics. Fraternal twins can have distinct personalities, talents, and physical characteristics, similar to any other siblings.
The term "fraternal twin" is commonly used in medical and biological contexts, as well as in everyday language to describe siblings born together who are not identical twins. Understanding the distinction between fraternal and identical twins is essential for differentiating the genetic and biological characteristics of multiple births.
The word "fraternal twin" derives from the Latin word "fraternus", meaning "brotherly". The term "fraternal" is used to describe twins who are not identical, as they develop from two separate fertilized eggs. The term emphasizes the sibling-like relationship between these twins.