Genius can be conceptualized as a 'genie' within us - the word genie being derived from the Roman concept of a guardian and tutelary spirit, akin to the Greek 'daemon' (like Socrates's daemon who advised him and give him insights) - the concept then gathering connotations of creativity, and then 'genie' being used for the Arabian Jinn, which are autonomous supernatural entities (some good, some evil).
I am coining a usage which somewhat playfully takes all these elements so as to indicate the way in which the creativity of a classic genius:
1. Guides the genius - not in all the minute and specific details of living, but in a long-term, strategic fashion
2. Has apparently 'supernatural' powers - since real creativity is ultimately mysterious, and
3. Acts somewhat like an independent and autonomous personage - with whom the conscious and rational mind must build a relationship (the conscious rational mind may influence but does not control the genie, and cannot force the genie to do his will).
My understanding is that - in the above sense - almost everybody will have a genie of creativity - but the genie will vary considerably in power and dominance - in most people the genie has modest power and is usually ignored or suppressed; in a great genius the genie will have great power and will tend to dominate life strategy in many ways.
(Other in-between and dissociated states are presumably possible.)
The genie of a normal (non-genius) person will only be apparent in short bursts and perhaps in a crisis. In a short term crisis a person may demonstrate remarkable and seemingly-inexplicable powers or abilities (which can look like sheer luck). This could be explained in terms of them drawing upon the mysterious insights, intuitions, and knowledge of their genie.
However, this state can seldom be maintained over the long term, because most people are set-up to be dominated not by the genie but instead by more 'normal' motivations - such as social esteem (e.g. the striving for status and admiration), familial and sexual motivations, comfort, convenience, excitement etc.
So, creative genius is quantitative - the genie varies in power and dominance - at at a certain degree of power and degree of dominance the genie will have 'taken-over' the life strategy of a person (not completely, but primarily) - and such as person is A Genius.
Why is this important?
Because we live in a society where, for whatever reason, genius tends to be unacknowledged, denied, ignored and even (but usually indirectly, for other and usually 'political' given-reasons) actively persecuted.
Also, because the world-historical geniuses, which for the past four hundred years used to be common in all major domains of life in The West - art, literature, science, medicine, law, politics, the military, and religion - has become extremely rare; indeed has almost disappeared.
Therefore - if modern society wishes to avail itself of the benefits that genius (and only genius) can bring (e.g. solving unyielding problems by intuitive insights, making breakthrough discoveries), then modernity needs to become more sensitive in its detection, acknowledgement and recognition of genius: this is so even from the perspective of pure self-interest.
Perhaps a starting point is to recognize our own individual creative genie - no matter how relatively feeble it may be, and how infrequently it becomes apparent - we may notice it when, in a crisis, we may, briefly, be able to do something rather extraordinary and inexplicable.