Can identical twins be a boy and a girl?

Question

I know the answer to this one, I want you to think though. After the post time runs out, if the correct answer was not given I will post it myself. It's pretty interesting.

More correctly, If by defintion identical twins means that the babies came from one egg and one sperm, is it possible to have a genetically male boy and a genetically female girl?

To answer this question you must dwelve deep into genetics. Do not get lost with semantics, it is not a question of whether you think two people look alike, rather of DNA.

Answer 1

Thank you for this question - upon reading your question, I thought it was a 'trick' or stupid question, but, in light of some additional research, I see that there can be some differences. Some people above have touched on the correct answer, but for a full explanation, keep reading. I myself am an "identical twin," so the subject intrigues me.

Part of the problem comes from an outdated method of labling a twin "identical" or "fraternal" - generally, it is considered than an identical twin has identical DNA, and therefore must, by definition be both males or both females. Identical twins must be monozygotic (come from one egg and sperm). Dizygotic twins come from two eggs and two sperm.There is also a possibility of a single egg splitting and then fertilized by two different sperm, which is "identical fraternal". The sperm provides the 23rd chromosone as either an x or a y, making the embryo xx (female) or xy (male).

There are two possiblities

Sometemes, an error can occur, and the egg could be fertilized as xxy - a condition known as Klinefelter Syndrome. If the egg then splits and one embryo 'loses' an x, then the male will stay as xxy, (and have some health problems) and the female will live a happy, healthy life as an xx.

In another instance, an egg could be fertilized correctly, with an xy, and after it splits, one could lose the y, causing a happy boy with xy, and a 'fragile x' (or Turners Syndrome) girl with a single x - these girls also have many health concerns.

However - even though these babies started as a single egg and sperm, their resultant DNA would not be identical - therefore, they are considered to be monozygotic, but not truly identical, according to the common definition.

There are very few of these cases, but they do exist!

Answer 2

No, since a girl will need 2 X chromosomes and a boy will need 1 X and 1 Y. The egg has always the X both need, and sperm can have either X (for the girl) or Y (for the boy). So, assuming that by "identical twins" you mean they come from the same sexual cells (that's the meaning of the term, but seems that many people here think it has to be with appearence), it is impossible.

Answer 3

No. Identical twins are only refered to those who look identical in all aspects, including gender (with the exception of finger prints, lip prints and the like).

Identical twins occur during the 4th week of a female's pregnancy, when the blastocyst cell that will give rise to the embryo divides into two and thus there are now two embryos, with the same genetic material, who will begin formin in the mother's womb at the same time.

The other type of twins, fraternal twins as some people call them, occur when two separate eggs called oocytes become fertilized by sperm. It is in circumstances like these that a birth of a girl and a boy occur. They are still twins, but they are not identical.

Answer 4

No, Because, If Your Born Twins As A Boy And A Girl, Your Automatically, Un-identical Twins.. [Fraternal twins]

You Can Look Alike, But They're Not Identical.

Answer 5

No... They can't. Not naturally, anyway. An identical twin comes from an already fertilized egg that splits to create two identical fetuses. Fraternal twins are two separate eggs that are fertilized independently of one another, and it is from this that the male-female twins come from. Now, something could happen in the womb and cause some mutation of one of the identical fetuses that could theoretically require surgery... I know that they usually default to a girl when something happens to the male parts of a baby. Or, someone could have a sex change. Apart from that, identical twins always start out identical in everything, including sex.

Answer 6

The genetic makeup of a female is XX and XY for a male.

So in the case of identical twins- meaning they share the same genetic makeup, this would be impossible!

Answer 7

NO! they cant be! coz, identical twins develop from only one zygote that is fertilised by d sperm. the zygote after growing till a certain stage divides itself into two equal parts with the same no. of cells! and by the time the sex of d foetus is already decided! as a result, the two foetus formed are of the same sex as the original zygote(since the cells n all d features of the two foetus are a copy of each other, their sex is also same)! thus, the two identical babies formed are either two girls or two boys! not a boy n a girl!!

Answer 8

Monozygotic twins are genetically identical (unless there has been a mutation in development) and they are the same gender. (On extremely rare occasions, an original XXY zygote may form monozygotic boy/girl twins by dropping the Y chromosome for one twin and the extra X chromosome for the other.)

Answer 9

Yes, Because it is very rare but it can happen you see when the XXY Zygote form the Monozygote boy/girl twin by dropping the y for one twin and the extra X for the other twin the key thing is the zygote and the extra x chromosone

Answer 10

It's rare, but it's happened. As a female who is genetically XY, trust me. Genes can't tell the whole story. Identical twins have identical genomes. They don't have to look alike.