The ODNB article was written by Peter D. G. Thomas He seems to be a specialist in the period and has written a monograph on Wilkes.The article cites several primary and secondary sources. It was last revised in 2008. I like to use ODNB as a starting point but it's worth considering that historians aren't necessarily interested in dates of birth.
DNB is very much earlier published in 1900, so I suspect that it was the source for the Britannica page from 1911,.
Personally, without an alternative primary source, I'd use ODNB as the more recent publication.
But it is interesting to contrast the two descriptions of his marriage
While still under age Wilkes married, in deference to his father's wishes, a woman ten years his senior,
This Dutch interlude ended when he was summoned back for an arranged marriage on 23 May 1747 to a bride some ten years older than himself...