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After all, while huge differences can and do happen with fraternal twins, identical twins are usually exactly that — identical in skin, hair and eye color. Even though this is true for all identical twins, we can’t usually tell because the changes happen in parts of the DNA that don’t affect how identical twins look.
Why do some twins look completely different?
As a result of the environment, chemicals called “epigenetic marks” attach to the chromosomes and can turn specific genes on or off. So identical twins with identical DNA may have different genes turned on, causing them to look and act differently, and even to develop different diseases such as cancer.
Can fraternal twins look completely different?
Fraternal twins can be the same or opposite sex and their genes are as different as any other brother and sister. Often, same-sex fraternal twins look different – for example, they might have different hair or eye colour. Occasionally they look quite similar.
Is it possible for twins not to look alike?
The most common type of twins are non-identical twins, which can be the same or different sexes. Non-identical twins are also known as fraternal twins or dizygotic twins (from two zygotes, what we call the earliest embryo when the egg and sperm fuse).
Can 1 identical twin have autism?
Studies in identical twins have shown that autism has a strong genetic basis: If one identical twin has autism, the other one has it, too, as much as 90 percent of the time. The new work supports these estimates: In 64 of the 78 twin pairs, both twins have an autism diagnosis.
Why are single births more common than twins?
Multiple births are more common than they used to be, due to the increased use of assisted reproductive techniques, in particular the use of fertility drugs. Older women are more likely to have a multiple pregnancy and, because the average age at which women give birth is rising, this is also a contributing factor.
Who determines twins mother or father?
For a given pregnancy, the odds of conceiving fraternal twins are only determined by the mother’s genetics, not the father’s. Fraternal twins happen when two eggs are simultaneously fertilised instead of just one.
Are Olsen twins identical or fraternal?
Mary-Kate and Ashley Olsen are not identical twins The Olsen twins still work together on their various fashion brands. However, they like to point out that they are two separate people. They are fraternal twins, not identical, as people usually assume since they look so much alike.
Why are identical twins not exactly?
It is true that identical twins share their DNA code with each other. This is because identical twins were formed from the exact same sperm and egg from their father and mother. However, in the case of identical twins, early in development, this embryo divides into two. This creates two babies rather than one.
How early is it safe to deliver twins?
The American College of Obstetricians and Gynecologists (ACOG), for example, recommends delivery between 34 and 37 weeks for twins with a shared placenta and at 38 weeks for twins with separate placentas. Some other physician groups recommend delivery closer to 39 weeks with separate placentas.
How do you know if pregnant with twins?
Early signs of a twin pregnancy include severe morning sickness, quick weight gain, and more breast tenderness. You may also notice an increased appetite or extreme fatigue. Plus, those who have a twin pregnancy may begin showing sooner.
What is the average gestation for twins?
A little more than half of twin pregnancies end in preterm delivery (before 37 weeks). While 40 weeks is the full gestation period of the average pregnancy, most twin pregnancies are delivered at approximately 36 weeks (range 32-38 weeks depending on the type of twin pregnancy).
Who carries the twin gene?
While men can carry the gene and pass it on to their daughters, a family history of twins doesn’t make them any more likely to have twins themselves. 3 But, if a father passes on the “twin gene” to his daughter, then she may have a higher chance than normal of having fraternal twins.
What are the odds of a twin having twins?
Here are the odds of having twins: 1 in 85 in general. 1 in 250 to have identical twins. 1 in 17 if the mother is a fraternal twin. 1 in 85 if the mother is an identical twin.
Could I be pregnant with twins again?
History of twins: Once you have a set of fraternal twins, you’re twice as likely to have another set in future pregnancies. Number of pregnancies: The more pregnancies you’ve had, the greater your chances of having twins.
Can you tell if twins are identical from ultrasound?
One of the major advances in distinguishing between the two types of twins has been the development of ultrasound. However, when a twin pregnancy is evaluated by ultrasound, it’s impossible to tell directly whether the twins are identical or fraternal.
Does twins have the same blood type?
5 Monozygotic (identical) twins will have the same blood type, with a few very rare exceptions. Dizygotic (fraternal) twins may have the same blood type, or they may have different types. However, twins with the same blood type can be either fraternal or identical.
Can you tell which identical twin is the father?
A standard paternity test could not tell which identical twin might be the dad. A standard paternity test relies on the differences between the DNA of two potential dads. And identical twins have so few that these tests miss them.
What are signs you’re having a boy?
It’s a boy if: You didn’t experience morning sickness in early pregnancy. Your baby’s heart rate is less than 140 beats per minute. You are carrying the extra weight out front. Your belly looks like a basketball. Your areolas have darkened considerably. You are carrying low. You are craving salty or sour foods.
Do you cramp more with twins?
With a twin pregnancy, your body makes high levels of pregnancy hormones. So morning sickness may come on earlier and stronger than if you were carrying a single baby. You may also have earlier and more intense symptoms from pregnancy, like swelling, heartburn, leg cramps, bladder discomfort, and sleep problems.
