The feelings are definitely influences by hormones. Doesn't make them any less real.
There is a ton of philosophy written around this. Feelings are a very self-centric view of the world. The goal of rationalization is to take a wider systemic view without being self-centered.
Because if you push feelings and chemistry to the max you could also make an argument that taking meth and heroin is the most important thing in the world, as the feelings coming out of it are very real.
Also, the context of this conversation was replying to this assertion:
> You don’t need children to have these sorts of feelings
So it's about feelings, not about "rational discussion". Not a "fallacy" like you claimed, but the actual topic of discussion.
>>> Raising kids is probably the most meaningful and significant thing I have done with my life.
Also, nobody here -- the people you're debating with, I mean -- is arguing that having kids is universally the most meaningful thing anyone can do with their life; they are instead offering their personal perspectives. For example, in the sentence you quote:
> Raising kids is probably the most meaningful and significant thing I have done with my life
The operating words are "I have done with my life"; it's not telling you what you should do with yours.
In fact, the whole debate in this sub-thread was sparked by a very aggressive comment (not yours), but which you chose to implicitly defend:
> You don’t need children to have these sorts of feelings, unless you can only get them from some small people who don’t have any choice but to love you.
Well, whether the person saying the above has or doesn't have children is entirely relevant. It's not a "fallacy". We're discussing feelings, even the above comment acknowledges it; and in relation to parenthood the fact remains: these feelings must be experienced, you cannot truly comment on them otherwise. I mean, you can, but your opinion wouldn't be of much value.
Read again the comment that prompted the above comment:
> What's so easy to miss is the immense feeling of love, of being needed, of being loved, that words can't describe. I frequently tell people I feel like the grinch after he discovers Xmas - my heart is three times bigger. But you can't really see that it's just a feeling I carry with me.
Really, it's all about subjective feelings. Which, essentially, is all that matters in the context of this conversation. If you don't have children, you won't have felt like this. You simply cannot. So it's not a fallacy to ask if you have them.
edit:
> a blog post that claims having kids is the most meaningful thing you can do with your life
The blog doesn't claim this, either.