LOUGHREA, IRELAND — The first message Cameo Wood received from Ireland had an air of mystery to it.

“We are trying to connect with members of the Ball family,” it read, naming her great-great-great-grandparents, Patrick and Margaret, and the parish where they had been buried, Kilchreest. “Contact me for more information.”

A resident of San Francisco, Ms. Wood is a hacker made good. Now on her “ninth or 10th” start-up, she and the rest of Silicon Valley are steadily recasting the future — but now she’s decided to learn more about her past.

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