I'm currently trying to develop the world of a sci-fi story I'm working on, and a concept I've thought of adopting with the environment and characters is a common breeding system where identical twins (or sometimes not, asymmetric twins from the same egg have also been under consideration) are a commonplace byproduct of the world's evolution.

I'd like to know the plausibility of this. My idea is for two twins to be born with natural, pheromonal connections between each another. The sexual organs of the twins would be the same, thus preventing immediate inbreeding. I'd also envisioned [most] twins consistently having lifelong reliance on one another. i.e. I also want to know how reasonable it would be to expect them to coordinate efforts in the acquisition of food and evade potential predators. As for mating, I thought if they shared the exact same DNA there would be less ingrained concern over which gets to spread its genes. Would this be accurate?

Thanks in advance for anyone that tries to answer me. I'm doing what I can to keep things in the realm of reality, so it'd be much appreciated to know whether or not the universe I'm creating has a strong enough footing in the real world.


closed as off-topic by Remi.b, kmm, David, theforestecologist, Satwik Pasani Apr 6 '18 at 14:24

  • This question does not appear to be about biology within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 4
    $\begingroup$ Welcome to Biology.SE. Your question appears to be a good fit for worldbuilding.SE but is rather off-topic here on Biology.SE. $\endgroup$ – Remi.b Apr 1 '18 at 15:06
  • $\begingroup$ Parthenogenesis, apomixis and fragmentation exist in many animal species. $\endgroup$ – Remi.b Apr 1 '18 at 15:07
  • $\begingroup$ Okay, I apologise. Thank you for pointing me to a more suitable venue. $\endgroup$ – Melvin T. Apr 2 '18 at 16:59

As a whole, your question is opinion-based, speculative and not really suitable for Bio-SE. However, several of the building blocks that you describe have a reasonable biological foundation, which might be useful to know.

For instance:

  • There seems to be a genetic component To monozygotic twinning (see e.g. ghr.nlm.nih.gov). This means that the trait could, very hypothetically, be selected for, and a population with a higher level of monozygotic (identical) twins could develop (ignoring other possible detrimental effects). Different frequencies of MZ twins is also know from castle breeds and other species.

  • The level of shared genes is the driving force between kin selection. This is part of the explanation for the reproductive system in social bees (and other eusocial insects), where (usually) a single queen reproduces and her workers (all sisters), which are 75% related to eachother due to the haplodiplod genetic makeup, all work towards the common "goal" of producing new sister queens (which will then be 75% related to all the workers).
    This gives some (again, very hypothetical) basis for your idea that "...they shared the exact same DNA there would be less ingrained concern over which gets to spread its genes".

  • Monozygotic twins often describe an especially strong sibling bond, which lends support (again, very hypoythetically) to your idea of "...expect them to coordinate efforts in the acquisition of food and evade potential predators.". There is also some research to back this up (e.g. Fortuna et al. 2011. Twin relationships: A comparison across monozygotic twins, dizygotic twins, and nontwin siblings in early childhood), but there are also studies that indicates that monozygotic twins show similar sibling behaviors as other types of sibling pairs (see e.g. Mark et al. 2017. Using Twins to Better Understand Sibling Relationships). This is not a field I know well and there is most certainly many more relevant sources to look at.

The introduction to Mark et al (2017) contains many references on MZ twins that should be relevant to your "thought experiment", e.g.:

...Fraley and Tancredy’s (2012) later work, which suggests that twin children rely more heavily on their co-twin for safety and security than do non-twin siblings.


Not the answer you're looking for? Browse other questions tagged or ask your own question.