I don't think sucking cock makes you gay. Plenty of straight guys suck cock and enjoy it. But at the end of the day, they will be in bed with a woman.
There is a difference between being sexually attracted to a guy and liking to have sex with a guy.
I am a fan of casual sex. I love having sex with another guy. I am not looking for a relationship. I am looking to get naked with a guy and enjoy ourselves. I am not bragging here, but I have had sex with at least 200 guys. Some people like drinking beer. Others like going to hockey games. I like having sex with a man and I love to suck a man's cock. This week is typical ... three guys came over here to have sex. They are all married to women, but they love having sex with another man ... me. I was also I was the third guy in a mmm threesome. One of the other two is s straight single who loves m2m sex.
At the end of the day, however, I will be sleeping with my partner ... the guy I have been in a relationship for over seven years. We love each other and are committed to each other. Yes, he has sex with other guys. So do I. I am gay and far prefer sex with a guy. He is bi and has sex with both.
Sucking cock does not make you gay. It is just a preference you have when you are having sex.