Origins
The English word 'genesis' descends from Greek 'génesis' (origin, creation, birth, becoming), derived from the verbal root 'gen-' (to beget, to produce), which traces back to the Proto-Indo-European root *ǵenh₁- (to beget, to give birth). This PIE root is arguably the single most productive root in the entire Indo-European family, with hundreds of descendants in virtually every branch.
The word entered English primarily through its use as the title of the first book of the Bible — the Book of Genesis, describing the creation of the world. In this biblical context, the word was known in English from the Old English period, borrowed through Latin from the Greek Septuagint translation of the Hebrew Bible. The more general use of 'genesis' as a common noun meaning 'origin' or 'coming into being' dates from the early seventeenth century.
The productivity of PIE *ǵenh₁- in English is extraordinary. Through the Greek branch, the root gave 'genesis,' 'gene' (a unit of heredity, coined in 1911 from German 'Gen'), 'genetic,' 'genotype,' and the '-gen' suffix used throughout chemistry: 'oxygen' (acid-producer), 'hydrogen' (water-producer), 'nitrogen' (niter-producer), 'pathogen' (disease-producer), and 'allergen.' Greek also gave 'eugenic' (well-born), 'genocide' (race-killing, coined in 1944), and the suffix '-geny' (as in 'phylogeny' and 'ontogeny').
Latin Roots
Through Latin, the same root produced an equally vast family. Latin 'genus' (kind, race, birth) gave English 'genus,' 'genre,' 'gender,' and 'general' (pertaining to the whole kind). Latin 'generāre' (to produce, to beget) gave 'generate,' 'generation,' 'generous' (originally meaning 'of noble birth'), and 'degenerate' (to fall from one's kind). Latin 'gēns' (clan, family) gave 'gentle' (originally 'of good birth'), 'genteel,' 'gentry,' and the name 'Gentile' (one of the nations, i.e., not Jewish). Latin 'genius' (the guardian spirit of a person or place, from the idea of a begetting spirit) gave English 'genius' and 'ingenious' (having inborn talent). Latin 'genuīnus' (innate, natural) gave 'genuine.'
Perhaps most remarkably, the same PIE root through its zero-grade form *ǵn̥h₁- produced Latin 'nāscī' (to be born), from an earlier *gnāscī. This gave English 'nascent' (being born), 'native' (born in a place), 'nature' (inborn quality), 'nation' (a people born together), 'natal,' 'prenatal,' 'neonatal,' 'innate,' 'cognate' (born together, hence related), and even 'naive' (through French, from Latin 'nātīvus'). The connection between 'genesis' and 'nature' is thus not merely thematic but literally etymological — they share the same root.
Through the Germanic branch, PIE *ǵenh₁- produced Old English 'cynn' (kin, kind, race), which gives Modern English 'kin,' 'kindred,' 'kind' (both the noun meaning 'type' and the adjective, originally meaning 'natural, innate'), and 'king' (literally 'the one of the kin,' the leader of the people). Thus 'genesis,' 'nature,' 'kin,' and 'king' are all descendants of the same PIE root, connected by the fundamental concept of birth and origin.
Greek Origins
In modern scientific usage, 'genesis' and its derivatives are indispensable. 'Biogenesis' (the origin of life from living matter), 'abiogenesis' (the origin of life from non-living matter), 'pathogenesis' (the origin of disease), 'morphogenesis' (the origin of form), and 'psychogenesis' (the origin of the psyche) all employ the Greek root in precise technical senses. The word 'epigenetics' — the study of heritable changes not involving alterations to the DNA sequence — combines 'epi-' (upon, above) with 'genetics,' adding yet another layer to this ancient root's modern career.
The breadth of this single etymological family — from 'kin' to 'king' to 'nature' to 'nation' to 'genesis' to 'gene' to 'oxygen' — illustrates how a single concept (birth, begetting, origin) can ramify through thousands of years and dozens of languages into an interconnected web of meaning that touches biology, chemistry, politics, philosophy, and everyday speech.