Jamesy wrote:
How can people tell by my posts on this website that i am childish and immature?

If they can tell, it is by your choice of words, how you express yourself and the topics you start or choose to respond to.
Your age or any other outward fact will only be a premature assumption.
In this post, the one you made here, I assume you're childish and immature - to some extent, anyway - because you say so yourself.
You don't write: "Why do they 'think' I'm childish and immature", but: "How can they tell...", and telling is finding out, noticing, i.e...
I don't think it means they don't like you, though.
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"One Law for the lion and the ox is oppression" W.Blake.
"Life itself is an exercise in Exceptions!" Capt. Picard (Star Trek - The Next Generation).