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Is It Doable for Twins to Have Totally different Fathers?

Twins happen when two infants are born to 1 mom after a single being pregnant. In the event that they’re equivalent (monozygotic), they shaped when one zygote, created with only one egg and one sperm, splits into two new eggs, leading to two embryos moderately than one. Every embryo then develops right into a separate fetus.

Fraternal (dizygotic) twins, in the meantime, happen when two separate eggs are fertilized by two separate sperm. Fraternal twins share solely 50% of the identical genes, whereas equivalent twins share 100%, which explains why fraternal twins normally do not look practically as alike as equivalent ones do.

Except a set of twins’ beginning mom served as a surrogate or used donor eggs, there could be no query that she’s the mom of each twins. However you could be left questioning: Can twins have totally different fathers? The reply is sure, however solely in instances by which they’re fraternal, as equivalent twins kind from a single egg/sperm mixture and thus can’t have totally different fathers.

Cultura RM / Jamie Kingham / Getty Photographs

Twins With Totally different Fathers

As know-how has improved the accuracy and accessibility of genetic testing, folks have been capable of obtain genetic testing to find out when fraternal twins have two totally different fathers. Fraternal twins are the results of hyperovulation, the discharge of a number of eggs in a single cycle. Superfecundation describes a scenario by which every of the eggs are fertilized by sperm from totally different males, main them to have totally different organic fathers (making the twins half-siblings). The suitable time period to explain this case is heteropaternal superfecundation.

There may be little analysis on the prevalence of heteropaternal superfecundation within the common inhabitants, however some researchers discovered that in a parentage take a look at database of 39,000 information, 2.4% of dizygotic twins whose dad and mom have been concerned in paternity fits have been a results of heteropaternal superfecundation.

Some researchers consider that the frequency of heteropaternal superfecundation, which is extensively assumed to be very uncommon, is underestimated within the common inhabitants.

Examples of Heteropaternal Superfecundation

A method heteropaternal superfecundation might happen is that if a girl has sexual activity with two totally different males throughout the similar timeframe that each embryos are conceived. For instance, in New Jersey, a mom of twins underwent paternity testing when making use of for public help. After the take a look at confirmed that her companion was solely the daddy of one in every of her twins, she admitted that she had had intercourse with one other man throughout the similar week that her twins have been conceived.

Equally, a mom of twins in Texas acknowledged that she was having an affair with one other man when her twins have been conceived. Paternity testing revealed that her fiancee was certainly the daddy of one of many twin boys, however that one other man was the organic father of the opposite twin.

Whereas we would assume all situations of twins with totally different fathers are the results of the mom having sexual activity with totally different companions, this is not the one situation by which it might occur. This example also can happen when twins are the results of fertility therapies. For instance, in a mixup at a lab, gear had been used twice, inflicting one other man’s sperm to be combined with that of the supposed father leading to Dutch twin boys conceived by way of in vitro fertilization (IVF) with totally different fathers.

How Paternity Testing Is Carried out

Paternity testing could be carried out both earlier than or after twins are born. Submit-natal paternity testing could be finished by amassing and testing blood from the newborn’s umbilical wire at beginning (a blood take a look at carried out at a lab) or a buccal (cheek) swab taken both at a lab or at dwelling after which later despatched to a lab. The presumed mom and father’s DNA is normally obtained this manner as properly.

Prenatal paternity testing is a little more sophisticated, nonetheless, and could be extra invasive relying on which methodology is carried out.

Non-Invasive Prenatal Paternity (NIPP)

This take a look at entails amassing blood from each the mom and the presumed father, which is then examined after preserving and analyzing the newborn’s DNA discovered within the mom’s bloodstream. It may be carried out any time after eight weeks of being pregnant and is 99.9% correct.


Amniocentesis entails a physician utilizing ultrasound know-how whereas inserting a skinny needle into your uterus by way of your stomach to attract amniotic fluid for genetic testing (most frequently used for prenatal analysis of chromosomal abnormalities and different medical situations within the fetus). This take a look at could be carried out within the second trimester and carries a small danger of hurt to the newborn and inflicting miscarriage.

Chorionic Villus Sampling (CVS)

Chorionic villus sampling (CVS) can be usually used to examine for chromosomal issues. It entails a physician inserting a skinny needle or tube guided by ultrasound from the vagina and thru the cervix to acquire chorionic villi, or small items of tissue connected to the uterine wall. The fetus and this tissue come from the identical fertilized egg and have the identical genetic make-up, thus permitting it for use for paternity testing in opposition to the alleged dad and mom’ DNA. CVS could be carried out earlier in a being pregnant, from weeks 10 to 13. As with amniocentesis, CVS poses a small danger of miscarriage, in addition to cramping, bleeding, and uterine an infection.

A Phrase From Verywell

As a result of all types of paternity testing will contain amassing DNA from each dad and mom, there could also be a clumsy dialog in some unspecified time in the future in your being pregnant or after the beginning of your twins if there’s any doubt over paternity. By researching your choices and making ready your self for the procedures and outcomes, you may make the method a bit much less demanding. As at all times, speak to your physician about any considerations relating to your being pregnant and any related procedures.

Verywell Household makes use of solely high-quality sources, together with peer-reviewed research, to help the details inside our articles. Learn our editorial course of to be taught extra about how we fact-check and preserve our content material correct, dependable, and reliable.
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  3. Segal NL, Craig JM, Umstad MP. Problem to the assumed rarity of heteropaternal superfecundation: Findings from a case report. Aust J Forensic Sci. 2019. doi:10.1080/00450618.2019.1616821

  4. Paddock C. Mom Offers Beginning To Twins With Totally different Fathers, US. MedicalNewsToday.

  5. Curry A. The world’s least alike twins. NBC Information.

  6. Tam JCW, Chan YM, Tsang SY, et al. Noninvasive prenatal paternity testing by way of SNP‐primarily based focused sequencing. Prenat Diagn. 2020;40:497-506. doi:10.1002/pd.5595

  7. Salomon LJ, Sotiriadis A, Wulff CB, Odibo A, Akolekar R. Danger of miscarriage following amniocentesis or chorionic villus sampling: Systematic evaluation of literature and up to date meta-analysis. Ultrasound Obstet Gynecol. 2019;54(4):442-451. doi:10.1002/uog.20353

By Pamela Prindle Fierro

 Pamela Prindle Fierro is the creator of a number of parenting books and the mom of dual ladies. 

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