Yes. An E-2 spouse is employment-authorized incident to status and may work in the family enterprise or for any other employer. Children may attend school but cannot work, and they lose E-2 dependant status at 21.
The spouse is free to work; the children face a deadline
E-2 dependant rules are among the most accommodating for a working spouse. Under current USCIS guidance, spouses of E-2 principals are authorized to work by virtue of their status and do not need a separate employment authorization document. A spouse can therefore manage the front desk of the family's U.S.
business, take a job with an unrelated employer, or continue self-employment, as long as any professional licensing requirements are met. Children under 21 may study at any level but may not work, including in the family business; a teenager helping at the counter is unauthorized employment. When a child turns 21, dependant status ends, and because E-2 carries no path to permanent residence, there is no pending immigrant petition to protect them.
A Lac-Beauport family with a 17-year-old should decide now whether that child will pursue a student classification, return to Canada for university, or qualify in their own right. The investor's own status is renewable indefinitely while the business qualifies, but it does not become permanent.