Does your family include a set of twins? Some say that the chance of having twins runs in some people’s families. A study looked at the genetics that influence the possibility of a woman having twins. Their study is very specific and might, or might not, relate to your family.
It has been said that the chance that a woman will have twins runs in families. Is that true? According to the NHS, in the UK, the answer is both yes and no. It depends, in part, of what sort of twins are being discussed.
The NHS says that there is no evidence that identical twins run in families. Identical twins happen when one fertilized embryo splits into two. Identical twins share the exact same DNA. This type of twin is also called monozygotic twins.
Non-identical twins, which are also called fraternal twins or dizygotic twins, share no more DNA than two typical siblings would. The NHS says that a couple is more likely to have a set of fraternal twins if there are other twins in the woman’s family.
A study done by researchers at the University of Florida found some other interesting information that could influence a woman’s chance of having twins. Unexpectedly, it appears that smoking is a factor. In other words, smoking is an environmental factor that influences whether or not a woman will have twins.
The study includes 277 participants who had completed a larger study of 2,200 African American mothers who had term or pre-term labor. The study also included African American women who had given birth to twins and African American women who had given birth to infants with extremely low birth weights.
Previous to this study, the researchers had demonstrated that there are significant differences in SNP frequencies in mothers of twins as compared to mothers of “singletons”. A SNP (pronounced “snip”) is a DNA sequence that happens when a single nucleotide in a person’s genetic code has a slight variation.
The researchers discovered that the relationship between smoking and the presence of a gene called TP53 increases the likelihood that an African American mother would have twins. The researchers described this relationship as “profoundly significant”.
It should be noted that this study came from a small sample of people, so further studies should be done on this topic. The most noteworthy thing from the study is the realization that there is a genetic variance in humans that can account for reducing, or increasing, the frequency of twins.
In short, it is true that fraternal twins tend to “run in the family”. This study shows that smoking, an environmental factor, can also influence the chance that a woman will have twins. At least, it does for the specific group of women who were in the study.
Image by sarahemcc on Flickr.
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