Can identical twins be different sexes?

No, typical identical twins are always the same sex because they come from one egg and one sperm, sharing the same sex chromosomes (XX or XY). However, in extremely rare cases, genetic mutations or events like gonadal dysgenesis can cause one twin to develop as male and the other as female (or intersex), even with identical DNA, though this is incredibly uncommon.

Can I identical twins be different genders?

Yes, identical twins can be different sexes, though it's extremely rare and happens due to genetic mutations or errors during the very early stages of development after the single fertilized egg splits, leading to different sex chromosomes or gene expressions, such as one twin being male (XY) and the other female (XO) with Turner Syndrome, or discordant gender identities.
 

Can identical twins be intersex?

Except in cases where an identical twin has ambiguous or intersex genitals, identical twins will be the same sex recorded at birth (two girls or two boys).

Why is intersex not considered a gender?

Gender isn't determined by your body or any physical attributes, so, just like non-intersex people, intersex people can be any gender! Sexuality is also separate from our bodies and gender identity. Intersex people can also be any sexuality, including asexual, bisexual, gay, lesbian, straight, or anything else!

What are two gender twins called?

Fraternal or 'dizygotic' twins

These babies will be no more alike than siblings born at separate times. The babies can be either the same sex or different sexes.

Can Identical Twins Be Different Gender? - Gender Equality Network

Why can't you say siamese twins?

You can still say "Siamese twins," but it's outdated and often seen as insensitive; the preferred term is conjoined twins, because "Siamese" refers specifically to Chang and Eng Bunker from Siam (now Thailand), and not all conjoined twins are from there, making the term inaccurate and potentially linking to past "freak show" exploitative contexts. Using "conjoined twins" is more precise, respectful, and inclusive of all cases, regardless of origin. 

Can two sperm enter one egg?

Yes, two sperm can fertilize one egg, a rare event called polyspermy, which usually leads to an unviable embryo with three sets of chromosomes, often causing early miscarriage. However, in extremely rare cases, it results in semi-identical twins (sesquizygotic twins), where a single egg is fertilized by two sperm, creating offspring sharing all maternal DNA but only some paternal DNA, a unique form of chimerism.
 

Can a boy and a girl be a twin?

Yes, boy/girl twins are very common with fraternal twins (non-identical) because they come from two separate eggs and sperm, like any siblings; but it's also extremely rare for identical twins (from one egg/sperm) to be different sexes due to rare genetic glitches.
 

Can identical twins have different fingerprints?

Yes, identical twins have different fingerprints, although their prints are very similar due to shared DNA; unique details like ridge endings and branching points (minutiae) are shaped by random environmental factors in the womb, such as umbilical cord length, pressure, and growth rates between weeks 13 and 19 of development, ensuring no two fingerprints are ever identical, even for twins. 

What is the average lifespan of identical twins?

During the 41-year follow-up for all-cause mortality in each of the four pairs studied, one co-twin was deceased (Figure 1). The average years of follow-up to death was 32.5. The average life for deceased twins was 74.8 years and the minimum life expectancy for the still alive twins was 81.4 years.

Can a baby have two fathers DNA?

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.

Who carries the gene for twins?

The tendency for fraternal twins is genetic and carried by the mother, specifically a gene for hyperovulation (releasing multiple eggs) that she inherits from her mother or father, but it's the woman who ovulates multiple eggs who has twins, not the father. A father can pass the gene to his daughters, increasing their chances, but his own family history of fraternal twins doesn't directly affect his partner's odds, though factors like age, diet, and fertility treatments also play a role. Identical twins, however, are generally not genetic and occur randomly when one fertilized egg splits.
 

What are semi-twins?

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.

Are Abby and Brittany legally two people?

Abby and Brittany are legally two separate people – except at work.

What if one conjoined twin dies?

If one conjoined twin dies, the surviving twin faces extreme risk, often from sepsis or organ failure due to shared blood supply, necessitating emergency surgical separation to remove the dead tissue, though this surgery itself is highly dangerous and can lead to the death of the survivor, highlighting the critical dependency in many conjoined pairs. Survival largely depends on shared anatomy, but the decaying tissue poisons the living twin, making swift action crucial for the best chance of survival, which remains low for many cases. 

How long is a twin pregnancy?

Twin pregnancies rarely last this long, with the typical twin pregnancy lasting 35 to 36 weeks. It's common to go into labor sooner. Few treatments are available to prevent preterm labor, and they're not always successful. Once you go into active labor, there's no way to stop labor from progressing.

Do twins have the same blood type?

**Identical twins (monozygotic) almost always have the same blood type because they share identical DNA from one fertilized egg, but fraternal twins (dizygotic) can have different blood types, just like any other siblings, as they come from two different eggs and sperm. Very rare genetic mutations or conditions like blood chimerism (sharing blood cells in the womb) can cause identical twins to have different blood types, but this is extremely uncommon. 

What are vanishing twins?

A vanishing twin, or Vanishing Twin Syndrome (VTS), is when one fetus in a multiple pregnancy (like twins) stops developing and disappears during early gestation, usually in the first trimester, with its tissue being reabsorbed by the mother or the surviving twin(s). This often happens without the mother knowing, though some experience mild bleeding or cramping, and it's diagnosed via ultrasound when an embryo seen early on is absent in later scans.
 

Are Mary Kate and Ashley actually fraternal?

Yes, Mary-Kate and Ashley Olsen are fraternal twins, not identical, meaning they developed from two separate eggs, though they look very similar. Key differences often cited include Mary-Kate being slightly taller and left-handed, while Ashley is right-handed. They've played roles together since infancy on Full House but have distinct personalities and careers as adults, operating as separate individuals.
 

What is a daisy baby?

A "Daisy Baby" is a term for babies affected by Twin to Twin Transfusion Syndrome (TTTS), a serious condition in identical twins sharing a placenta, or related complications like TAPS, SIUGR, and TRAP. The name comes from the Twin to Twin Transfusion Syndrome Foundation (TTTSF), symbolizing twins thriving like daisies after surviving the "storm" of the condition, with their logo often showing two daisies from one stem, representing the shared life and journey. 

Is homosexuality more common in twins?

Yes, studies consistently show homosexuality is more common in identical (monozygotic) twins than in fraternal (dizygotic) twins, indicating a genetic component, though not 100% genetic, as identical twins aren't always concordant for being gay. If one identical twin is gay, the other is significantly more likely to be, compared to fraternal twins where genes are less identical, highlighting the role of genetics alongside other factors.
 

Can two sperm fertilize one egg?

Yes, two sperm can fertilize one egg, a rare event called polyspermy, which usually leads to an unviable embryo with three sets of chromosomes, often causing early miscarriage. However, in extremely rare cases, it results in semi-identical twins (sesquizygotic twins), where a single egg is fertilized by two sperm, creating offspring sharing all maternal DNA but only some paternal DNA, a unique form of chimerism.
 

Can two men make a woman pregnant at the same time?

In order for heteropaternal superfecundation to happen, a woman first needs to be experiencing hyperovulation. She then needs to have sex with two different men, both of whom need to be producing viable sperm.