Yes, provided the investment meets the ordinary tests: the full qualifying amount placed at risk in a new commercial enterprise, ten full-time jobs for qualifying US workers, lawful source of funds, and the investors' engagement in management or policy. The son's role neither helps nor disqualifies the petition; his job simply does not count.
Family ties are neutral; the business must stand alone
The rules do not prohibit investing in a business managed by a relative. What they require is that the capital be genuinely at risk in that enterprise, meaning equity or a contribution with no guaranteed return, not a loan to the son that he will repay. The enterprise must be a new commercial enterprise, which includes a start-up formed recently or an existing business that is restructured or expanded in the ways the regulations describe.
Job creation is measured by full-time positions filled by US citizens, permanent residents or other authorized workers; the son, unless he is already a qualifying US worker, is not counted, and the investors themselves are never counted. Engagement in management can be satisfied by holding director or manager rights with genuine authority over policy, which is easy to document in an operating agreement but must actually be exercised. Approaching the petition as a business investment first makes it easier to satisfy each element.