No, identical twins are almost always the same sex (boy/boy or girl/girl) because they come from one split egg with identical DNA; boy/girl twins are typically fraternal (non-identical) from two eggs, but in extremely rare cases (like Turner Syndrome or genetic mutations), a boy/girl identical pair can occur, though this is exceptionally rare.
Because identical twins share all of their genes, they cannot be opposite sexes. To understand what happened, doctors took samples of the amniotic fluid. They found that the twins shared 100% of their mother's genes, but only 78% of their father's.
Approximately 33% of twins are identical (same gender) and 66% are fraternal. Fraternal twins can be the same gender or different genders. The chances of fraternal twins being different genders is approximately 50%.
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.
Key Takeaways. Since they come from the same fertilized egg, identical twins have the same sex chromosomes. Fraternal twins come from two separate eggs, so they can be any combination: girl/girl, boy/boy, or boy/girl. Different-sex identical twins are extremely rare.
Sex determination in twins occurs as normal, with males having XY and females having XX. The sex of a fetus, even twins, can be identified via an ultrasound at week 14-21 of the pregnancy. Twins can consist of males, females, or both, with female twins being the most common.
Among monozygotic twins, in extremely rare cases, twins have been born with different sexes (one male, one female). When monozygotic twins are born with different sexes it is because of chromosomal defects.
A daisy baby is another name for babies with TTTS. The Twin-to-Twin Transfusion Syndrome Foundation coined the term after its founder planted daisy seeds with her surviving twin son in their backyard. The daisy field is a symbol of hope that all babies affected by TTTS will survive.
With identical twins, one egg is fertilized by one sperm, and the embryo splits at some later stage to become two. Occasionally, two sperm are known to fertilize a single egg; this 'double fertilization' is thought to happen in about 1% of human conceptions.
The gene for hyperovulation can come from either side of the family, but the woman would need to have the gene in order for the couple to have twins based on genetics. In other words, twins on the father's side of the family will have no influence on your chances of having twins.
Fraternal twins can look alike as much as two siblings can look alike.
What will help boost my chances of having twins?
Fraternal twins, in which each of two eggs is fertilized by a different sperm cell, occur in about four of every 1000 births. About half of those result in male-female twin pairs.
Identical, or monozygotic (MZ), twins have 100 percent of their genes—including those that influence risk for alcoholism—in common, whereas fraternal, or dizygotic (DZ), twins share (on average) only 50 percent of the genes that vary in the population (see figure). Common Environmental Sources.
So in almost all cases, a biological female will have two X chromosomes and a biological male will have one X and one Y chromosome. These variations in X and Y chromosomes mean that brothers and sisters can never have identical genotypes.
For a given pregnancy, the odds of conceiving fraternal twins are only determined by the mother's genetics, not the father's.
Monoamniotic twins are identical twins that share an amniotic sac, the fluid-filled sac that holds the baby during pregnancy (also known as the “bag of waters”). Normally, identical twins each have their own amniotic sac. Monoamniotic twins are a rare type of “monochorionic” twins, meaning they also share a placenta.
Heteropaternal superfecundation is an extremely rare phenomenon that occurs when a second ova released during the same menstrual cycle is additionally fertilized by the sperm cells of a different man in separate sexual intercourse taking place within a short period of time from the first one 1-4.
There are many different kinds of twins, including fraternal twins (two eggs and two sperm), identical twins (one egg and one sperm), mirror image identical twins (separation on day 5 of development), identical twins with two placentas, one placenta and two sacs, one placenta and one sac, and finally conjoined ...
Mary-Kate and Ashley Olsen look identical, but they're actually not. The Olsen twins are fraternal twins; according to E!, Mary-Kate is 1 inch taller than Ashley. After sharing the role of Michelle Tanner on ABC's "Full House, " the Olsen twins continued their acting careers side-by-side.
Fraternal twins are as alike as siblings would be—in other words, they're not identical. Fraternal twins might be two boys, two girls, or a boy and a girl.
Does having twins skip a generation? Fraternal twin pregnancies result from hyperovulation of the mother. The father's sperm does not decrease or increase the chance of having twins. Skipping a generation can happen in some cases, depending on whether the twins are boys or girls.
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).