Straight sex is when a guy is attracted towards a girl or is in a sexual relationship with a girl. Heterosexual and straight are interchangeable in most contexts. Straight certainly means “exclusively attracted to the opposite sex.” Thus, a straight woman is attracted to men, and not women.
There are other sexual orientations except being straight for ex. gay (men who are attracted towards men), lesbianism (women attracted towards women) and many more. We need to understand that all orientations are perfectly normal. We also should avoid any discrimination towards any group which in my opinion is an abnormal behavior.      
 Please see these links bellow for more information…
https://letstalksexuality.com/diversity-sexual-orientations/
https://letstalksexuality.com/sexuality-alice-walker/