c. 1200, from Old English cynn "family; race; kind, sort, rank; nature" (also "gender, sex," a sense obsolete since Middle English), from Proto-Germanic *kunja- "family" (source also of Old Frisian kenn, Old Saxon kunni "kin, kind, race, tribe," Old Norse kyn, Old High German chunni "kin, race;" Danish kjön, Swedish kön, Middle Dutch, Dutch kunne "sex, gender;" Gothic kuni "family, race," Old Norse kundr "son," German Kind "child"), from PIE root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups.
In the Teutonic word, as in Latin genus and Greek [genos], three main senses appear, (1) race or stock, (2) class or kind, (3) gender or sex .... [OED]
Related to both words kind and to child. From 1590s as an adjective, from the noun and as a shortening of akin. Legal next of kin (1540s) does not include the widow, "she being specifically provided for by the law as widow" [Century Dictionary], and must be a blood relation of the deceased.
"a thing of the same kind as, or nearly allied to, another," 1730s, from French congénère (16c.), from Latin congener "of the same race or kind," from assimilated form of com "with, together" (see con-) + gener-, stem of genus "race, kind" (from PIE root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups). Related: Congenerous (1640s); congeneracy.
Used as temporary fencing in agriculture. Sense of "barrier to jump in a race" is by 1822 (hurdle-race also is from 1822); hurdles as a type of race (originally horse race) with hurdles as obstacles is attested by 1836. Figurative sense of "obstacle" is 1924.