All marriages between first cousins are prohibited.
Idaho Code § 32-206
[(32-206) 1866, p. 71, sec. 3; R.S., sec. 2425; reen. R.C. & C.L., sec. 2616; C.S., sec. 4596; am. 1921, ch. 115, sec. 1, p. 291; I.C.A., sec. 31-206; am. 1959, ch. 44, sec. 1, p. 89.]