I find that E and K (who are 15 months apart) are often mistaken for twins- likely because E is small and K is bigger for her age since they don't look a ton alike. I honestly find it weird since E is a very advanced talker for 3 and K is behind the curve for 20 months and K just LOOKS more baby to me (mommy goggles? haha).
Do your sibsets get mistaken for twins a lot? Do you think they look like twins? Or do you stare at people like, "What are you talking about?!" haha