Well here's a story from a different point of view, not long after we'd had our kids my wife 'volunteered' me to lesbian friends (both doctors and lawyers were involved) - I've always been the known male donor, not a mystery, but emphatically not a parent, more like an uncle.
It's worked out really well for us, our kids got half siblings (again more like cousins), some extra sets of doting grandparents etc etc
As modern families shrink, with 1 or 2 kids we don't have as many relatives (it's a power series sort of thing) extended families shrink, we got to enlarge ours. Usually you only get one chance in life to choose who your relatives are, we found a second.
It's worked out really well for us, our kids got half siblings (again more like cousins), some extra sets of doting grandparents etc etc
As modern families shrink, with 1 or 2 kids we don't have as many relatives (it's a power series sort of thing) extended families shrink, we got to enlarge ours. Usually you only get one chance in life to choose who your relatives are, we found a second.