In ordinary English, "grooming" is when a social superior (in some sense) does normal, legal things to encourage a person to follow a certain path, e.g. "groomed him to take over the company". It has recently gained a secondary meaning of befriending a minor for illicit sexual purposes, but that sense is clearly not applicable here. Instead, Dave has encouraged Bob to commit illegal acts.
Although serious childhood abuse could constitute a mitigating factor in the case of Bob committing a crime as an adult, there are typically statutory statements as to what factors are relevant. Here is the Washington state list, which is suggestive, not exhaustive:
(a) To a significant degree, the victim was an initiator, willing
participant, aggressor, or provoker of the incident. (b) Before
detection, the defendant compensated, or made a good faith effort to
compensate, the victim of the criminal conduct for any damage or
injury sustained. (c) The defendant committed the crime under duress,
coercion, threat, or compulsion insufficient to constitute a complete
defense but which significantly affected his or her conduct. (d) The
defendant, with no apparent predisposition to do so, was induced by
others to participate in the crime. (e) The defendant's capacity to
appreciate the wrongfulness of his or her conduct, or to conform his
or her conduct to the requirements of the law, was significantly
impaired. Voluntary use of drugs or alcohol is excluded. (f) The
offense was principally accomplished by another person and the
defendant manifested extreme caution or sincere concern for the safety
or well-being of the victim. (g) The operation of the multiple offense
policy of RCW 9.94A.589 results in a presumptive sentence that is
clearly excessive in light of the purpose of this chapter, as
expressed in RCW 9.94A.010. (h) The defendant or the defendant's
children suffered a continuing pattern of physical or sexual abuse by
the victim of the offense and the offense is a response to that abuse.
(i) The defendant was making a good faith effort to obtain or provide
medical assistance for someone who is experiencing a drug-related
overdose. (j) The current offense involved domestic violence, as
defined in RCW 10.99.020, and the defendant suffered a continuing
pattern of coercion, control, or abuse by the victim of the offense
and the offense is a response to that coercion, control, or abuse. (k)
The defendant was convicted of vehicular homicide, by the operation of
a vehicle in a reckless manner and has committed no other previous
serious traffic offenses as defined in RCW 9.94A.030, and the sentence
is clearly excessive in light of the purpose of this chapter, as
expressed in RCW 9.94A.010.
The only clause that comes close, and it is not close enough, is
(h) The defendant or the defendant's children suffered a continuing
pattern of physical or sexual abuse by the victim of the offense and
the offense is a response to that abuse
Being badly brought up is not a mitigating factor for sentencing, and certainly not a defense.