trezor.io
Rate this file (Rating : 5 / 5 with 1 votes)
twin sisters
trezor.io

Twin Sisters

Human twin studies
Twin studies are utilized in an attempt to determine how much of a particular trait is attributable to either genetics or environmental influence. These studies compare monozygotic and dizygotic twins for medical, genetic, or psychological characteristics to try to isolate genetic influence from epigenetic and environmental influence. Twins that have been separated early in life and raised in separate households are especially sought-after for these studies, which have been used widely in the exploration of human nature. However, the utility and accuracy of these twin studies has been called into question and remains controversial. Classical twin studies have are now being supplemented with molecular genetic studies which identify individual genes.
• Unusual twinnings
Among dizygotic twins, in rare cases, the eggs are fertilized at different times with two or more acts of sexual intercourse, either within one menstrual cycle (superfecundation) or, even more rarely, later on in the pregnancy (superfetation). This can lead to the possibility of a woman carrying fraternal twins with different fathers (that is, half-siblings). This phenomenon is known as heteropaternal superfecundation. One 1992 study estimates that the frequency of heteropaternal superfecundation among dizygotic twins whose parents were involved in paternity suits was approximately 2.4%.

File information
Filename:286638.jpg
Album name:People & Humanity
Rating (1 votes):55555
Keywords:#twin #sisters
Filesize:50 KiB
Date added:Jun 24, 2010
Dimensions:464 x 600 pixels
Displayed:37 times
URL:displayimage.php?pid=286638
Favorites:Add to Favorites