There are several examples of sons or daughters of Heroes (people with powers). Micah is the son of D.L. Hawkins and Niki Sanders. Claire Bennett is the daughter of Meredith Gordon. It is unknown whether the unborn child of Janice and Matt Parkman will have powers.
Also, siblings seem to have an opportunity to have powers, but it does not guarantee powers. Nathan Petrelli and Peter Petrelli are brothers that have powers. It is unknown whether Jessica Sanders had powers before her death. Her sister Niki Sanders, however, has powers through her alternate personality, Jessica. It is hypothesized that Mohinder's sister, Shanti, had powers (was "special", inspired father's research), however Mohinder has not shown any evidence of powers to date.