No. No. No.

That's not it at all.
A surprising number of women watch lesbian porn. That's a fact.
The only people (in my experience) that say they are 100% straight are either homophobes (I'm not saying that's you) or are people who have just lived a very straight life, most people do at some point in their lives find some kind of attraction to someone of the same sex in my experience, some will write it off as whatever they can convince themselves it was. Some people will engage it and take it further some people will just put it down to one of those things.
The main problem is defining sexual attraction, does it have to mean physical sexual arousal? Because I'm often sexually attracted to people without getting a massive erection etc. Or is it a set of thoughts? Well alot of people have attractive personalities, but at what definable point does it go from being attracted to them, wanting to be a friend or being attracted to their confidence, how they hold themselves to being sexually attracted to them.
It's all a grey area, it's all a blurred line, some people accept it, some people repress it, some people try to suppress it in others. Some people never knowing understand what they are experiencing. Human psychology is never black and white, no one is 100% anything. It's not an on off switch, nothing in psychology is, it's a spectrum.