Actually, punk is more a derivative of ska than the other way around.
Ska is like the rebellious music of Jamaicans circa the late 1960s as opposed to reggae music. It appealed to over-worked, lower class youths. They became known as "rude boys", having thier own sense of fashion, talk, and demeanor.
I could go on forever, but just peep this site.
http://users.bigpond.net.au/lvisser/skahistory.html
In a matter of speaking, ska would've been in heavy swing when a certain youth named Kool Herc was growing up in Jamaica. In relevance, this minor attachment could be what your friend is referring to, as it is known that Kool Herc is indeed "the Grandfather of Hip hop".
