Can brother and sister be identical twins?

In 99.9% of cases boy/girl twins are non-identical. However, in some extremely rare cases resulting from a genetic mutation, identical twins from an egg and sperm which began as male (XY) can develop into a male / female pair.

What are twins that are brother and sister called?

Definition. Fraternal twins (also called dizygotic twins) result from the fertilization of two separate eggs with two different sperm during the same pregnancy. Fraternal twins may not have the same sex or appearance. They share half their genomes, just like any other siblings.

Is it possible for two siblings to be identical?

Identical twins are the only siblings that share 100% of their DNA. Non-identical brothers and sisters share about 50% of inherited gene variants, which is why siblings and fraternal twins can be so different.

Is identical twins can be boy and girl?

Identical, or monozygotic, twins may or may not share the same amniotic sac, depending on how early the single fertilized egg divides into 2. 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.

What is a mirror twin?

The term mirror twin is used to describe a type of identical, or monozygotic, twin pairing in which the twins are matched as if they're looking into a mirror — with defining characteristics like birthmarks, dominant hands, or other features on opposite sides.

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What are the 3 types of twins?

Finding out you're having a baby is one of the most exciting times in your life.

Can you have twin half siblings?

Homopaternal superfecundation is fertilization of two separate ova from the same father, leading to fraternal twins, while heteropaternal superfecundation is a form of atypical twinning where, genetically, the twins are half siblings – sharing the same mother, but with different fathers.

What's the closest two siblings can be?

It's technically possible for two siblings to be as close as 9 or 10 months apart. After your pregnancy comes to an end, you'll start ovulating again before you have your first postpartum period.

Are twin half siblings possible?

One egg was fertilized by A.S.'s sperm, and the other was fertilized by the other man's sperm. Though they are twins, the girls born of this heteropaternal superfecundation occurrence are only half-sisters.

Can 2 sperm fertilize the same egg?

Occasionally, two sperm are known to fertilize a single egg; this 'double fertilization' is thought to happen in about 1% of human conceptions. An embryo created this way doesn't usually survive, but a few cases are known to have made it — these children are chimaeras of cells with X and Y chromosomes.

What are 5 identical siblings called?

Quintuplets occur naturally in 1 in 55,000,000 births. The first quintuplets known to survive infancy were the identical female Canadian Dionne Quintuplets, born in 1934. Quintuplets are sometimes referred to as "quins" in the UK and "quints" in North America.

Can a baby have 2 fathers?

Although this is quite rare it can happen and it's called superfetation. Two babies are conceived from separate acts in two different cycles. These babies can be from the same father or two different men. When heteropaternal superfecundation occurs, the babies are from different fathers.

Can siblings be born 12 months apart?

The term “Irish twins” refers to one mother having two children who were born 12 months or less apart.

Can a brother and sister conceive a child?

The simple, clinical answer to the question is: Yes. A brother and sister can have a perfectly healthy child together. Children born of incestuous couplings do have an increased risk of presenting genetic defects and/or deformities. But the increased risk is negligible with first generation inbreeding.

What is the shortest age gap between siblings?

It's technically possible for two siblings to be as close as 9 or 10 months apart. After your pregnancy comes to an end, you'll start ovulating again before you have your first postpartum period.

What happens if 2 siblings have a child?

The risk for passing down a genetic disease is much higher for siblings than first cousins. To be more specific, two siblings who have kids together have a higher chance of passing on a recessive disease to their kids.

What is the best age gap between kids?

Based on the study findings, they suggest the optimal time between giving birth and getting pregnant again is 18 months, with a range of 12 to 24 months. That said, many experts still adhere to the recommendation of 18 to 24 months.

What are polar twins?

Polar twins. Polar twins share the same chromosomes from their birthing parent, but they get different chromosomes from their non-birthing parent. This is because they're created from a single egg but two separate sperm.

How much DNA do brothers and sisters share?

Because of recombination, siblings only share about 50 percent of the same DNA, on average, Dennis says. So while biological siblings have the same family tree, their genetic code might be different in at least one of the areas looked at in a given test. That's true even for fraternal twins.

Can twins have 2 different fathers?

In rare cases, fraternal twins can be born from two different fathers in a phenomenon called heteropaternal superfecundation. Although uncommon, rare cases have been documented where a woman is pregnant by two different men at the same time.

What is the riskiest type of twins?

One placenta and one amniotic sac.

This is the riskiest and rarest type of twin pregnancy. Fetal complications can arise due to tangling of the umbilical cords or an imbalance in nutrients, blood or other vital life supporting systems.

Which parent decides twins?

However, for a given pregnancy, only the mother's genetics matter. Fraternal twins happen when two eggs are simultaneously fertilized instead of just one. A father's genes can't make a woman release two eggs.

Which twin is conceived first?

In the majority of vaginal births, Baby A is born first. But occasionally the twins switch positions at the last minute, and Baby B emerges first, as further noted by the Stanford Medicine News Center. Still, the birth order is relatively straightforward.

What is a chimera baby?

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.)