Write a story about this for us. I have a friend who discovered, at ~45, that she had 'another family', somewhere in the midwest. Her only sister had died young, so this was a real joy for her.
And all the stories we've seen about people finding half-siblings - sometimes 50 or more - via the net... from anonymous fathers who donated sperm. Imagine a room full of strangers who all acted sorta like you!
I have an older brother that I haven't seen in at least 10 years. We aren't that close, but I was amazed at how similar we acted - even dressed in the same style of evening-casual shirt.