I don't know if we are born cocksuckers but there is definitely a latent desire for another man's cock. As a teen I loved wrestling one of my friends because he always wanted to put me in a tight head scissor. I don't think I was conscious of the reason why I let him trap me for 10-15 minutes at a time was that his cock was inches from my face. Then in my thirties I noticed that I was becoming more aware of the man's cock and less interested in tits when I watched porn.
I have shared in other posts about the guy who fed me his cock so I won't repeat it here--but the abridged version is that he came to my house to quote on furniture repair wearing threadbare jeans with a noticeably large bulge. My eyes wandered and he knew he had me and he fed me his load in my garage. He told me that most men (90% in his words) are submissive to alpha males like him and can easily be converted to cocksuckers.
@Oldcowboy has commented how amazed he is at the number of men that will submit to his cock. I love reading his posts as his words usually gets me all worked up.
Maybe it is an awakening to the latent cocksucker that is in the vast majority of us men. I'm not sure it matters, the fact is there are a ton of cocksuckers compared to the number of dominant men that feed us.
I was married when I sucked my Dom's cock but I have considered myself a cocksucker from that point and I feel no shame in my desire to be on my knees in front of a beautiful cock. I do regret that the next time he reached out to me I said 'no' and he never responded to me again. A valuable lesson for me that if I am serving an alpha male he must be a priority or he will cast me aside.