These are some cool facts about the type of twins Ava and Emma are:
Incidence
Monozygotic twinning occurs in birthing at a rate of about three in every 1000 deliveries worldwide,[13]
The likelihood of a single fertilization resulting in MZ twins is uniformly distributed in all populations around the world.[11] This is in marked contrast to DZ twinning, which ranges from about six per thousand births in Japan (almost similar to the rate of MZ twins, which is around 4–5) to 15 and more per thousand in some parts of India[15] and up to 24 in the US, which might mainly be due to IVF (in vitro fertilisation). The exact cause for the splitting of a zygote or embryo is unknown.
In-vitro fertilization techniques are more likely to create twins. Only about three pairs of twins per 1,000 deliveries occur as a result of natural conception, while for IVF deliveries, there are nearly 21 pairs of twins for every 1,000.[16]
Genetic and epigenetic similarity
Monozygotic twins are genetically identical (unless there has been a mutation during development) and they are almost always the same sex. On rare occasions, monozygotic twins may express different phenotypes (normally due to an environmental factor or the deactivation of different X chromosomes in monozygotic female twins), and in some extremely rare cases, due to aneuploidy, twins may express different sexual phenotypes, normally due to an XXY Klinefelter's syndrome zygote splitting unevenly.[17][18]
Monozygotic twins have nearly identical DNA, but differing environmental influences throughout their lives affect which genes are switched on or off. This is called epigenetic modification. A study of 80 pairs of human twins ranging in age from three to 74 showed that the youngest twins have relatively few epigenetic differences. The number of epigenetic differences between MZ twins increases with age. Fifty-year-old twins had over three times the epigenetic difference of three-year-old twins. Twins who had spent their lives apart (such as those adopted by two different sets of parents at birth) had the greatest difference.[19] However, certain characteristics become more alike as twins age, such as IQ and personality.[20][21] This phenomenon illustrates the influence of genetics in many aspects of human characteristics and behaviour.
Phenotype similarity
Monozygotic twins are almost always the same sex and their traits and physical appearances are very similar but not exactly the same.[22]
Monozygotic twins look alike, although they do not have the same fingerprints (which are environmental as well as genetic). As they mature, MZ twins often become less alike because of lifestyle choices or external influences. The children of MZ twins would test genetically as half-siblings rather than first cousins.
Monochorionic-Diamniotic
Monochorionic twins share the same placenta.
Monochorionic twins generally have two amniotic sacs (called Monochorionic-Diamniotic "MoDi"), which occurs in 60–70% of the pregnancies with monozygotic twins.[25] Monochorionic-Diamniotic twins are almost always monozygotic, with a few exceptions where the blastocysts have fused.[23]
Egg Spilts: Days 4-8
I thought it was an interesting bit of facts. Just so everyone know as well we didn't have any help having twins. It just sorta happened lol.
