Henry Cavendish mụrụ na 10 Ọktoba 1731 na Nice, ebe ezinụlọ ya bi n'oge ahụ. Nne ya bụ Lady Anne de Grey, nwa nwanyị nke anọ nke Henry Grey, 1st Duke nke Kent, na nna ya bụ Lord Charles Cavendish, nwa nwoke nke atọ nke William Cavendish, 2nd Duke nke Devonshire. Ezinụlọ ahụ gbasoro usoro ọmụmụ ya n'ime narị afọ asatọ ruo n'oge Norman, ma jikọtara ya na ọtụtụ ezinụlọ aristocratic nke Great Britain. Nne Henry nwụrụ na 1733, ọnwa atọ mgbe amuchara nwa ya nwoke nke abụọ, Frederick, na obere oge tupu ụbọchị ọmụmụ nke abụọ nke Henry, na-ahapụ Lord Charles Cavendish ịzụlite ụmụ ya nwoke abụọ. A na-akpọ Cavendish dị ka "The Honourable Henry Cavendish". Site na afọ 11 gara ụlọ akwụkwọ Henry nke New, ụlọ akwụkwọ onwe ya dị nso na London. Mgbe ọ dị afọ 18 na Cambridge (na November 24, 1748) ọ banyere na Mahadum St Peter's College na Cambridge, ebe ọ nọ na-ewere ogo nke nna ya.
Afọ 1748