How do you know your straight?

Answer 1

You just...know. Of course it's not always that simple, many people will go through phases (especially in their teens) when they are confused about their sexuality and plenty of straight people can have crushes or interact romantically/sexually with people of the same sex/gender. There are terms such as 'questioning' to define people who maybe aren't sure what sexuality they fall into, and that's fine because you don't owe anyone a term.