Identical twins share the same genomes and are always of the same sex. In contrast, fraternal (
Although discordant karyotypes are known in identical twins, cases involving differences in sex phenotype are rare. We studied identical twins with the 46,XY karyotype - a male with mixed gonadal dysgenesis and a female with "pure" gonadal dysgenesis.
It is estimated that 99.9% of identical twins have the same gender. But, semi-identical twins are so rare that they make up only about 0.1% of the twin populations.
Monoamniotic-monochorionic Twins
This is the rarest type of twin, and it means a riskier pregnancy as the babies can get tangled in their own umbilical cords. If you have monoamniotic-monochorionic twins, your healthcare provider will monitor your pregnancy closely.
Fraternal twins live longer than singletons and identical twins longer still. Male identical twins on average, saw the most benefit. The rarity of twins has inspired many myths about them.
The first wife (died ante 1770), of Feodor Vassilyev (b. 1707–c. 1782), a peasant from Shuya, Russia, gave birth to 16 sets of twins.
Semi-identical twins are rare, and doctors say they've identified the second case ever | CNN. You've probably heard of identical and fraternal twins, but a report released this week says there's a third kind -- sesquizygous twins or "semi-identical." Researchers say they share anywhere from 50 to 100% of their genomes.
They come from the same fertilized egg and share the same genetic blueprint. To a standard DNA test, they are indistinguishable. But any forensics expert will tell you that there is at least one surefire way to tell them apart: identical twins do not have matching fingerprints.
If one egg is fertilised by two sperm, it results in three sets of chromosomes, rather than the standard two - one from the mother and two from the father. And, according to researchers, three sets of chromosomes are "typically incompatible with life and embryos do not usually survive".
Identical (i.e., monozygotic, or MZ) twins share 100 percent of their genes, whereas fraternal (i.e., dizygotic, or DZ) twins generally share only 50 percent of their genes.
Thus identical twins, though they start with the same genes, likely develop different personalities in the same environment partially based on how they interact with their environment.
Twins — even identical twins — don't have identical dental patterns, according to a study published in a 1982 issue of the Journal of the American Dental Association.
If twins are a boy and a girl, clearly they are fraternal twins, as they do not have the same DNA. A boy has XY chromosomes and a girl has XX chromosomes. Girl-boy twins occur when one X egg is fertilized with an X sperm, and a Y sperm fertilizes the other X egg.
Possibly every parents worse fear once they find out their multiples are identical is “how will I tell them apart?”. Don't panic, at some stage it will happen and you will get them mixed up. And in most cases its not the end of the world.
Conjoined twins are identical twins that don't completely separate from each other because the fertilized ovum fails to fully divide.
A rainbow baby is a child born after the loss of a previous pregnancy or newborn.
Chimerism occurs when a woman is pregnant with twins and one embryo dies, and the other embryo absorbs the twin's cells. (Scientifically speaking, this type of chimerism is called tetragametic because the baby was derived from four gametes – one egg and one sperm for each embryo.)
Race. African-American people assigned female at birth are more likely to have twins than any other race. Asian Americans and Native Americans have the lowest rates for twins. White people assigned female at birth have the highest rate of higher-order multiple births (triplets or more).
The man who is thought to have fathered the most children of all time is Moroccan Sultan Ismail Ibn Sharif (1645 to 1727) with a total of more than 1,000, according to Guinness World Records.
How many babies were born during the longest recorded human pregnancy? The longest recorded human pregnancy was 375 days, or just over 12 and a half months, according to Guinness World Records. During this pregnancy, a woman named Beulah Hunter gave birth to a healthy baby girl in 1945.
The DNA of monozygotic twins tends not to be 100% identical, and epigenetic and environmental differences further widen the gap between twin pairs. It's not nature or nurture; it's a complex interaction between our genes, our environment, and our epigenetic markers that shape who we are and what illnesses befall us.