As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood.
As a parent of twins, I'm pretty sure that you know the answer to the question “which twin is older?” It is, of course, the child that was born first.
Knowing which twin is the older one is usually a no-brainer. The time of birth is recorded, and whichever one is born first is officially the eldest.
Most twin, triplet or more babies will be slightly different in size, but sometimes 1 baby is significantly smaller than the other/s. This is called 'selective' fetal growth restriction. Selective fetal growth restriction occurs in 10-20% of multiple pregnancies. Find out more about fetal growth restriction.
Yes, some types of twins run in families. Non-identical (fraternal) twins tend to be hereditary.
However, since only women ovulate, the connection is only valid on the mother's side of the family. While men can carry the gene and pass it on to their daughters, a family history of twins doesn't make them any more likely to have twins themselves.
However, only women ovulate. So, the mother's genes control this and the fathers don't. This is why having a background of twins in the family matters only if it is on the mother's side. And why your son's family genetics did not play a role in his twins.
In addition, previous studies have shown that first-born twins are, on average, taller and heavier than second-born twins until adolescence (Silventoinen et al., 2007; Pietiläinen et al., 2002).
For vaginal delivery of both infants, the twins decide birth order by their placement in the uterus. Once the babies are large enough to stay in one position in the womb, the twin lowest in the uterus is known as Baby A and the one furthest from there is Baby B, according to the Stanford Medicine News Center.
Ultrasound exams are performed regularly to calculate the twins' weights and watch their growth and fluid levels. Although the smaller twin's growth may be somewhat restricted, in most cases the smaller twin will grow well enough to function normally.
There is one particular power though which twins possess, longevity. Fraternal twins live longer than singletons and identical twins longer still. Male identical twins on average, saw the most benefit. The rarity of twins has inspired many myths about them.
On September 1, sisters Umeno Sumiyama and Koume Kodama turned 107 years and 300 days old, officially breaking the record for the world's oldest living identical twins. The Japanese siblings are also the oldest identical twins to have ever lived.
It is likely that twins' awareness of one another starts sooner than seven or eight months of age. An article by the late doctor, T. Berry Brazelton, observed that at age three to four months, an infant identical female twin seemed disoriented when her sister was removed from the room.
Such twins, known scientifically as 'MoMo', an abbreviation for monoamniotic-monochorionic, are some of the rarest types of twins, making up less than one percent of all births in the United States, noted the statement.
This belief is based on the assumption that twinning is genetic and runs in families. However, if that was truly the case—if there was a twin gene—then twins would occur with predictable frequency in those families that carry the gene. There is no concrete scientific evidence that suggests twins skip a generation.
A 2019 study backed that up. For twins, birth order can influence dominance, says Nancy Segal, professor of psychology and director of the Twin Studies Center at Cal State Fullerton. Continue reading in Psychology Today.
Raising one child is difficult enough and changes your life forever. But raising twins can be even more overwhelming. While having two babies brings unique challenges, it can also bring twice the amount of joy.
Monoamniotic-monochorionic Twins
These types of twins share a chorion, placenta, and an amniotic sac. This is the rarest type of twin, and it means a riskier pregnancy as the babies can get tangled in their own umbilical cords.
Factors that increase the chance of twins include: consuming high amounts of dairy foods, being over the age of 30, and conceiving while breastfeeding. Many fertility drugs including Clomid, Gonal-F, and Follistim also increase the odds of a twin pregnancy.
The fixed-effects regression analysis of the sibships that included both twins and singletons showed that the twins were 0.9 cm (95% confidence interval: 0.6, 1.2) shorter than were their singleton brothers.
The DNA of monozygotic twins tends not to be 100% identical, and epigenetic and environmental differences further widen the gap between twin pairs. It's not nature or nurture; it's a complex interaction between our genes, our environment, and our epigenetic markers that shape who we are and what illnesses befall us.
However, few genes appear to be definitively linked to hyperovulation, so it could just be that genetics in general on the mother's side contribute to the probability of having fraternal twins. Heredity on the father's side, on the other hand, does not increase a couple's odds of having twins.
Twins are more or less equally likely to be female or male. Contrary to popular belief, the incidence of twins doesn't skip generations.