can twins be identical if they are boy and girl?
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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. ... The normal genetic make-up of a girl is XX.
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Identical twins are also known as monozygotic twins. They result from the fertilization of a single egg that splits in two. Identical twins share all of their genes and are always of the same sex.
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Identical twins generally have the same sex, eye and hair color, as well as blood type. Their physical features look typically the same, with most twins having an exact mirror face of the other.
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Non-identical, or dizygotic, twins occur when two separate eggs are fertilised, each by a different sperm, and develop in the womb at the same time. These twins can be the same or different sexes and are no more alike than any brother or sister, despite being born together.
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Though fraternal twins are together even in the womb, they are as genetically alike as any other normal brother and sister. That is, they don't necessarily share the exact same features as their twin, like most identical twins do.
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Fraternal twins may be the same gender, they may have many of the same characteristics, but also may be very different from each other and, in fact, share half of their genes just like their sisters and brothers.
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Do identical twins have the same dick sizes? They will be similar in size, even so similar as to appearing identical but there can be variations within the size. ... So in a way, yes they will have sizes really close to being identical assuming they were raised under similar situations.
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technically not possible. Conjoined twins are identical twins, coming from the same fertilised egg so they will always be the same sex because their sex was determined at the point of fertilisation from the male sperm. ... This could happen with conjoined twins, and you could end up with what looks like a boy and a girl.
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Monozygotic twins are genetically nearly identical and they are always the same sex unless there has been a mutation during development. ... Monozygotic twins, although genetically very similar, are not genetically exactly the same.
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Conjoined twins, whose skin and internal organs are fused together, are rare. ... As they come from the same egg, conjoined twins are genetically identical and always the same sex. Despite this, the surgeon at Sadar Hospital maintains in this case the twins could be of different genders.
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But then, somewhere along the way, the fertilized egg divides into two, resulting in identical twins. The chances of having identical twins is relatively rare — around 3 or 4 in every 1,000 births. And while it may be obvious, identical twins are always the same sex, either both boys or both girls, at birth.
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These twins can be the same or different sexes and are no more alike than any brother or sister, despite being born together. In this case of semi-identical, or sesquizygotic, twins, the egg is thought to have been fertilised simultaneously by two sperm before it divided.
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Fraternal twins Because they come from different eggs and sperm, they only share about 50 percent of their chromosomes like any other siblings. This means they can be the same or different sexes and aren't identical.
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And since brothers and sisters can have different blood types, so too can fraternal twins. It is a different story if the twins are identical. Identical twins come from the same egg and the same sperm and so share nearly identical DNA.
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Originally Answered: Can two people born like two years apart, be twins? No. Twins are genetically identical siblings or siblings born from the same pregnancy.
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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. But, actually, twins who start out with identical DNA always have slightly different DNA by the time they're born.
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It's extremely rare; less than 10 cases have been confirmed. Given the odds, it's safe to assume that 99.9 percent of all boy/girl twins are fraternal.