Ken Griffey Jr. -- My Son Chose Football ... And I'm Cool With It

His FATHER was a baseball star. HE was a baseball star. But Ken Griffey Jr.'s son WON'T carry on the MLB legacy 'cause he chose football instead ... and KG2 tells TMZ he's totally cool with it.

Turns out, Ken's kid Trey Griffey is a freshman wide receiver for the University of Arizona ... and Ken's in L.A. to watch the Wildcats take on USC tonight.

But when we asked if he was a little disappointed that his 6'3", 190 pound kid won't be following in his Major League footsteps, Ken gave a pretty heartfelt reply.

"He loves football ... and as a parent, I've got to be supportive of that," Ken told us ... adding, "You can't tell your child what to love and not to love."

But that's not all ... we also asked Ken about his kid's chances of making the NFL, if he considers himself the greatest HR hitter of his generation, and his encounter with Charlie Sheen.