From what I can tell I don't think Starship Troopers had any real negative effect on any of us in here (I might even suggest that questioning your personal ethics and politics should start quite young), I would certainly hand it to any teenager that was interested in Sci-fi. Other than that most of what I would put here are repeats of earlier choices:
"Ender's Game" is great, dark, but great.
"Pastwatch" is really good too.
"Snow Crash" and the "Diamond Age" (as with the two above) are rewarding in different ways each time you read them, you take
different things, so I would recommend them as soon as possible.
Anything by Keith Laumer, Walter Jon Williams is fun and covers a lot of ground. Eric Frank Russell had some great ones including the brilliant "Wasp" (also anyone that enjoyed the McCaffrey's Rowan series should read "Sentinel's from Space"), Gordon R Dickson's Dorsai series, and though I am loath to admit it here, the original 2 Warhammer 40k books Inquisitor and Deathwing I remember enjoying a lot.
All I would say is that I don't think you could go wrong with short stories by any reputable author, they rarely have time to be too dark, so are a good introduction to more adult themes without throwing them in at the deep end.
I'll shut up now as I could really go on forever.
Canada has announced it will build North America's biggest solar power plant - a 40MW project covering 365 hectares with around one million solar panels, Reuters reports.
My sister opened a computer store in Hawaii. She sells C shells down by the seashore.