I am the youngest in my family, and amongst my siblings my advice and input is valued at zero, because they pretty much treat me like I am still 11. This came up in spades when we planned my parents 50th anniversary.
I married the oldest in her family. She is one of six, and was basically Mom jr. to a lot of her siblings. Because of that, and my general prudence I am sought after adviser and have spent many an hour ginning up small spreadsheets to help people budget or re-write a resume or even counsel on relationships. Its really strange to live this double life. Part of it is cultural. Hers is a lively italian family, mine is a bit WASP-ie.
My father is a big Ayn Rand style libertarian, and his ethos of letting people make their own choices has a big impact too. When my leg was amputated at 22, dosed in morphine I had decide on whether to try to save the limb or surgically sever it. My entire family would not express a single opinion on the topic. It was 100% up to me. I get the idea (not to decide for me), but I could have used a little advice then. I went with the amputation, if you are curious.
Other than advising my wife's family I don't really give advice to others. And certainly don't meddle. It doesn't change anything. If a person is receptive, I think I can have an influence. But it comes mostly from them, not me.