[someguydave]

Quite so. Most twin studies on the subject turn up similar findings: https://evolutionistx.wordpress.com/2015/10/02/time-preferen...

"The best fitting model for 41 key studies (58 independent samples from 14 month old infants to adults; N=27,147) included equal proportions of variance due to genetic (0.50) and non-shared environmental (0.50) influences, with genetic effects being both additive (0.38) and non-additive (0.12). Shared environmental effects were unimportant in explaining individual differences in impulsivity."

So impulsivity (which is obviously closely related to your propensity to betray the trust of your fellow-man for a short-term gain) appears to be a combination of genetics and random luck (non-shared environment).