Green’s Dictionary of Slang

brothers and sisters n.

[rhy. sl.]

(US) whiskers.

[Aus]Sun. Times (Perth) 17 Mar. 21/3: What about ‘brothers and sisters’ for whiskers!
[US]T.A. Dorgan in Zwilling TAD Lex. (1993) 20: Brothers and sisters, that’s the whiskers.
[US]M.C. Sharpe Chicago May: Her Story in Hamilton (1952) 132: Brothers and sisters – whiskers.
[US]A.J. Pollock Und. Speaks 14/1: Brothers and sisters, whiskers.
[UK]P. Wright Cockney Dialect and Sl. 105: brovvers n’ sisters ‘whiskers’.