Probably not. There are some restrictions after JFK picked his brother as Attorney General, but that doesn't apply to a situation in which a presidential nominee picks a sibling for an elected position, where the voters make the final decision.
There were always ways around anti-nepotism laws. Jared Kushner became the Director of the Office of American Innovation. Hillary Clinton chaired the Task Force on National Health Care Reform.
https://www.npr.org/2016/11/18/50263...om-the-white-h
One potential issue with a running mate from your family (beyond voters thinking it's dumb) is that electors aren't allowed to vote for two candidates from their state for President and Vice President. The electors from Florida would not be able to vote for a Floridian for President and Vice President (this is why Texas resident Dick Cheney changed his voting registration to Wyoming to serve as George W Bush's running mate) so that could be a complication.
https://******.com/article/bf748a5fb...403182fd3cf591
My guess is that after Trump improved his numbers with voters of color in 2020, he'd pick an African-American or Hispanic running mate in 2024.