Lack of guilt is related to psychopathy, although there could be other reasons for it, e.g. ideological self-justifications, like breaking a law you don't agree with. Psychopathy is partially inheritable, which means the genetically-unexplained variance is usually attributed to enivronmetal differences.
The propensity for guiltlessness is part of a narrower trait (of psychopathy) called "callous-unemotional traits", and these can be identified around the age of 7, according to one (fairly cited) study of Viding
et al. (2005). Although the abstract of this paper is a bit... abstract, its intro is a bit more insightful what it is talking about:
‘Mark does not feel guilty if he has done something
wrong, he does not show feelings or emotions, and he
is rarely helpful if someone is hurt.’ This description
of one of the 7-year-old children (name changed) in
our twin study captures the core emotional impairment
of individuals with psychopathy. Psychopathy
in both childhood (psychopathic tendencies) and
adulthood involves both affective-interpersonal
impairment (callous-unemotional traits; e.g., lack of
empathy, lack of guilt, shallow emotions) and overt
antisocial behaviour.