Most of the 9 famous people born in Waterdown came into the world between Confederation and 1913

Carter Verhaeghe (Canadian ice hockey player) comes first, by the number of Wikipedia languages that cover them. Next come Alexander Ingram Fisher and Bill Ricker.

Of the 12 Wikidata puts here, the rest have no English or French article that confirms it.

33% of the list, where Canadian towns come to 2%.

George Davidson Grant (1870). At the other end, the youngest was born in 2000.

Anyone Wikidata records as born at a place inside Waterdown’s neighbourhood outline (the census tracts it is drawn from), hospitals and districts within it included, whose English or French Wikipedia article confirms it. People who only lived here, adult performers and people known mainly for crimes are left out. A neighbourhood page lists only births recorded in that neighbourhood; someone recorded as born just “in Toronto”, “in Montréal” or another split city stays on the city’s page.

The likeliest reasons: a birthplace recorded only as a province or as Canada, a hamlet or rural area with no page of its own, or an article that gives another place or none. Fixing Wikidata or Wikipedia brings them onto the list at the next refresh, as long as the two then agree.