Earlier quoted context omitted.
I'm pretty sure that the (presumed) father would be heavily invested in his kid, regardless of whether or not he gave him a job while he was in HS. Certainly we should look at someone else's (especially a relative's) corroboration of the story with some skepticism; ideally we could see the emails themselves. But really, OP should contact a lawyer ASAP.
Right, but I do think that the fact that he gave his son a job in high school makes his testimony even more unreliable than a typical parental relationship. Maybe the kid really is that good, but it's more likely that the dad was willing to sacrifice a bit of his company's time to support his son. That's not a decision that every father would make—not even every supportive father—so I think it's relevant here.
I haven't looked to see what position the son has at his father's business or the nature of the business itself so I can't comment on specifics. I will say, however, that it isn't uncommon for parents to employ their kids under the table for below market wage commensurate with their lack of experience. If a job gets half done for a quarter of the cost (no taxes, benefits, etc) then for many people it's a win, not to mention that the employer/parent has a captive employee and the employee/kid has early job history and walking around money.