Do you know your twin IRL? Have you at least dated them?

I take it for granted that all people here have or have had an in person mutual relationship with their twin but I also read of people that never met their TF in person or that never dated/kissed/had a relationship with them and consider an acquaintance or a stranger their TF.

Do you know your twin IRL? Have you at least dated them? If you don’t, what made you confident they are your TF?