I don't want to end the buzz around childhood memories, but business are legal entities/organizations, I really think lemonade stands and mowing lawns should not count as start-ups :/
Most articles I've read link successful startups to founders aged 30+. In fact, in this data from less than 2 months ago (from Founders Institute) - http://techcrunch.com/2011/05/28/peak-age-entrepreneurship/, the under 20s are less than 1%. This poll looks seriously skewed. Maybe the older, more successful entrepreneurs are busy with their work, and not here reading HN (oops)?
I think it's more that HN commenters skew younger, so you see a peak in mid-20's.
But anyway, I disagree with lemonade stands/mowing lawns not counting. You can learn a lot from the simplest business. And that knowledge (hopefully) causes you to avoid making the same mistakes later when there's much more at stake. That, and remember that most startups aren't financially successful anyway.
They do count in this sense, but the term start-up is being stretched thin (not only here on HN). I guess a more appropriate question to these answers would be "what was your first business experience?"
The poll measures first startups, not all startups. Since successful founders have often started less successful ventures previously, the data makes more sense than you'd think.
Most articles I've read link successful startups to founders aged 30+. In fact, in this data from less than 2 months ago (from Founders Institute) - http://techcrunch.com/2011/05/28/peak-age-entrepreneurship/, the under 20s are less than 1%. This poll looks seriously skewed. Maybe the older, more successful entrepreneurs are busy with their work, and not here reading HN (oops)?