I believe that lawyers rarely go to work for the federal government because the money's better. They go because there is less stress and more time for family. At least that's true for the government attorneys I know.
A lot of the lawyers I've known in gov't service are adrenaline junkies. Very early in their careers they were were faced with a choice:
A)Wall Street and earning $200,000+ a year doing contracts and IPOs
B)$40,000 a year putting bad guys in jail.
Not even a choice. They went for the $40,000.
A couple of them I knew had a father or uncle in law, but they were a distinct exception.
Only knew a couple of guys who'd worked for major law firms before coming into the government.