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.