The kids are all right. They just want to meet their dad. Last year’s fictional family comedy about sperm-donor kids and this-right-here documentary — as cheery and bittersweet and lovely-melancholy as can be — are surely the first indications of a wave of cultural angst over the rise in sperm-donation as a thing. Because the first major generation of those donor-conceived kids are young adults now, and they’re curious about their roots, as most people are. It’s not a bad sort of angst, but it is a uniquely high-tech, 21st-century one playing out on a large enough scale to be something we’ll have to think about… particularly since — as we learn here, via filmmaker Jerry Rothwell, who handles the subject with a smart balance of humor and alarm — the agencies that handled the distribution of these genetic donations appear to have had profits rather than people as their primary concern. Rothwell starts with 20-year-old JoEllen Marsh, wise beyond her years, who has always known she was donor-conceived and sets out to discover if she has any half-siblings who share the same genetic father. She finds one, and rejoices in a new sibling, and The New York Times catches on, connecting the tale to Donor 150, aka Jeffrey Harrison, once a philosophy major and exotic dancer with spiritual aspirations, now a Venice Beach bum who lives in a broken-down camper with little dogs and rescued pigeons. He’s a sweet, odd soul; his donor kids — who grow in number as the film unfurls — are so delightfully like him in many ways, and so uniquely themselves in those mysterious, wonderful ways that children always distinguish themselves from their parents. Is this the new definition of family? Dozens of brothers and sisters you never suspected existed become both reason to celebrate — yea! people who are like you in ways you never expected! — and to fret: what if you accidentally date one of your secret siblings? Everyone here is left to grapple with what it all means… as we are, too. It’s not at all an unpleasant prospect to see the world changing in such very small and yet such very striking ways, or to see real people try to keep up with it.