1590s, "native, produced within," also "inherent by nature," from in + bred. The genetic sense is attested from 1892 (see inbreeding).
Entries linking to inbred
in adv., prep.
a Middle English merger of Old English in (prep.) "in, into, upon, on, at, among; about, during;" and Old English inne (adv.) "within, inside," from Proto-Germanic *in (source also of Old Frisian, Dutch, German, Gothic in, Old Norse i), from PIE root *en "in." The simpler form took on both senses in Middle English.
Sense distinction between in and on is from later Middle English, and nuances in use of in and at still distinguish British and American English (in school/at school). Sometimes in Middle English shortened to i.
The noun sense of "influence, access (to power or authorities)," as in have an in with, is first recorded 1929 in American English. to be in for it "certain to meet with something unpleasant" is from 1690s. To be in with "on friendly terms with" is from 1670s. Ins and outs "intricacies, complications of an action or course" is from 1660s. In-and-out (n.) "copulation" is attested from 1610s.
bred adj.
"reared, brought up," 1650s, past-participle adjective from breed (v.).
inbreeding n.
"breeding of animals from the same parentage," c. 1842, from in + verbal noun from breed (v.). The older term for "to breed from animals of the same parentage" was to breed in and in (1765). The verb inbreed is attested from 1590s in the sense "produce within" (intransitive).