Do genius and genuine come from the same root? How closely related are they?

There is a probably a connection via the Latin word gignere "beget, produce".

According to the Online Etymology Dictionary genius is:

quote:

1390, from L. genius "guardian deity or spirit which watches over each person from birth; spirit, incarnation, wit, talent," from root of gignere "beget, produce" (see kin), from PIE base *gen- "produce." Meaning "person of natural intelligence or talent" first recorded 1649.

The same source says for genuine:

quote:

1596, from L. genuinus "native, natural," from root of gignere "beget" (see genus), perhaps infl. in form by contrasting adulterinus "spurious." Alternative etymology is from L. genu "knee," from an ancient custom of a father acknowledging paternity of a newborn by placing it on his knee.

The original meaning was 'inborn', making it likely the supposed connexion with genu 'knee' is spurious. However, the -u- in the word is unexpected: the root gen- 'be born', shouldn't evince that, whereas 'knee' would.

However, there is a parallel in ossuary: the Latin root for 'bone' shouldn't ever give a stem with a -u-, but it does here, and it's clear it's just a re-formation: there's no other root contaminating it.

Welcome back, aput. You've been missed. There is an old (at least medieval) folk etymology that relates knees and genitalia. The zodiacal sign of Capricorn ruling both parts of the body.